We present a novel approach that introduces mass as a fundamental metric for characterizing the size and structure of pigments and nanoparticles. This offers the potential to establish a new standard for particle size determination. Leveraging measurement techniques developed in aerosol sciences, we apply them to uniquely analyze pigment particles in an application-oriented manner.

Engineered nanomaterials are produced at a massive scale, ranging from 10³ to 10⁷ tons per year. The physical properties of individual particles, aggregates, fibers, etc., profoundly influence the application performance of these materials. Traditional methods for characterizing physical dimensions are either expensive and time-consuming (e.g., TEM imaging) or limited to equivalent diameters. For instance, laser diffraction size analysis requires the refractive indices for a wide range of color pigments and struggles to accurately measure nonspherical or aggregated particles.

Moreover, various material properties are mass-based metrics, facilitating the calculation of other essential values. For instance, using skeletal density (g/cm³) or specific surface area (m²/g), one can derive absolute particle volume or surface area and key performance indicators like the number of particles per gram or particles per dollar. Additionally, we measure the mobility diameter, enabling the calculation of particle bulk densities, fractality, porosities, and more.

To introduce the potential of this measurement concept, we present the results of three commercially available iron red pigments, three carbon blacks, and a coated iron yellow pigment. First, some background information is provided on the relation between particle mass and diameter, collectively defining the particle structure, and then the experimental setup is briefly discussed.

Background: Mass Plus Diameter Equals Structure

The structure of a particle population is encoded in the relation between mass and diameter of the individual particles. The scaling relation between particle mass (m) and the particle diameter (d) can be expressed by Equation (1):

with a constant (k) and the fractal index (fi). While a fractal index of 3 indicates scaling of a solid object, a fractal index below 3 (and above 2, which would indicate plate-like scaling) signifies the scaling of an increasingly more porous material (see Figure A1). In the context of color pigments, the fractal index describes the branching of the aggregates itself and varies for every material. To visualize that, we examine the effective density, i.e., the density of a particle with mass m and diameter d assuming sphericity. Inserting Equation (1) for the diameter gives Equation (2).

The scaling for three structurally different particle types is illustrated in Figure 1. Solid particles with a fractal index of 3 exhibit a constant effective density (in this special case, equal to the skeletal density). The effective densities of aggregated particles, here, as the example shows, columns and spheres (Figure 1), decreases with increasing mass, indicating a fractal index below 3. The stronger the decrease, the lower the fractal index and the higher the aggregation level of the particles.

FIGURE 1 Particle effective density as a function of particle mass for three structurally different particle types: Solid spheres (top), aggregated columns (middle), and aggregated spheres (bottom). Gray circles indicate a diameter estimate for visual guidance. Note: Same skeletal density is assumed. Particle mass axis is logarithmic.

The electrical mobility analysis is used to measure the geometric dimensions of a particle. Unlike other diameter estimates, the mobility diameter is not affected by the material density and refractive index. The mass is an intrinsic property of a particle and, unlike any equivalent diameter, it does not require any prior assumption and is independent of the measurement method. Therefore, the particle mass is well-suited to serve as a standard for the particle size.

Methods

We utilized a PowMaster system (femtoG AG, Switzerland), a combination of dedicated particle dispersion systems and the newly developed Mass & Mobility Aerosol Spectrometer (M2AS, Cambustion Ltd., UK), which enables the rapid measurement of size distributions for both absolute particle mass and a diameter (electrical mobility) within 5 to 15 minutes.

Powder analysis was initiated by an aerosolization of the powder material. Here we suspended 0.2 g of a pigment in 100 mL ultrapure water. The particles were deagglomerated by a finger-type ultrasound probe until an energy input of 100 J/ml was reached. Subsequently, the suspension was nebulized and the droplets were dried to retrieve the initial pigment particles. By producing small droplets and working with dilute suspensions, re-agglomeration during the drying process could be prevented.

Assuming that paint chemistry, film thickness, and application techniques are matched to the intended service environment, the degree of cure is the single most important characteristic required for a painted system to perform well. During the coating development phase, proper curing parameters are determined through a variety of sophisticated techniques monitoring the glass transition temperature. Thermomechanical Analysis (ASTM E1545) and/or Differential Scanning Calorimetry/Differential Thermal Analysis (E1356) are the usual methods for dissecting the degree of cure on a molecular level to inform the needed curing temperature and time information. Unfortunately, each of these techniques takes a fair amount of time that is inconsequential in a laboratory environment, but impractical for the fastpaced need of a production setting.

Testing has been developed to harness the laboratory curing information by correlating the glass transition temperature with a solvent (resistance) rub test. The standard for this testing is ASTM D5402 Standard Practice for Assessing the Solvent Resistance of Organic Coatings Using Solvent Rubs.

This is a quick way for a production quality lab to simulate the degree of cure by measuring the number of double solvent rubs it takes to damage the surface. This manual method is quick, surprisingly simple, and exhibits a 95% confidence limit for reproducibility between round robin operators. Coating thickness is also an important variable. Thicker coatings provide higher rub numbers because it takes longer to expose the substrate. Very thin films with pencil hardness of 6H fall a little outside of the 95% confidence limit, at 90%. The film thickness range required number of rubs and type of solvent are listed on the Technical Data Sheet.

Historically, many quick property tests were developed within the coil coating industry where 40,000+ pound coils take only minutes to run through the line, with mere seconds of curing time. This production cycle requires the absolute minimal test completion time. In 1980, the test was codified as National Coil Coating Association No. 11-18. Revised in June 1996, it became NCCA Technical Bulletin 4.2.11 Test Method for Evaluation of Solvent Resistance by Solvent Rub. In 1993, ASTM D5402 was written for use in the laboratory, the field, or the factory.

Coatings that chemically change during the curing process become more resistant to solvents as they cure. They reach specific levels of solvent resistance prior to topcoating or being placed into service. Epoxies, vinyl esters, polyesters, alkyds, and urethanes are typical chemistries that fit this paradigm. In this standard, no solvent is specified. Rather, the producer and user agree on the solvent and the number of double rubs based on formulation chemistry.

ASTM Test Method D4752 Standard Practice for Measuring MEK Resistance of Ethyl Silicate (Inorganics) Zinc-Rich Primers by Solvent Rub is the preferred solvent rub method for ethyl silicate zinc-rich primers as the cure is a reaction with moisture, providing a binder. In this case, MEK is the specified solvent correlating very well with the chemical changes occurring during cure as identified by diffuse reflectance infrared spectroscopy.

The test is remarkably simple. First, the dry film thickness is verified to be within the required range. Cheesecloth is saturated with the solvent of choice. An index finger is placed in the center of the cloth, with the thumb and remaining fingers holding the cloth in place. The index finger is held at an approximately 43° angle as the cloth is rubbed onto the paint, first away from the operator, then back over the same line. The complete forward and back motion takes about one second. The testing continues, adding solvent as needed without lifting the finger off the substrate until either the required double rubs are achieved or the substrate surface is exposed. If the substrate is exposed before the required number of rubs, this is reported as a failure.

In addition to reporting the number of double rubs, sometimes a rating system is used to further describe any damage to the surface, such as burnishing, marring, or depressions in the film, particularly in zinc-rich systems.

In 2013, a mechanical rubbing machine was developed and codified through ASTM D7835/D7835M Standard Test Method for Determining the Solvent Resistance of an Organic Coating using a Mechanical Rubbing Machine. It provides consistent stroke length, rate, pressure, and contact area not subject to variables such as human fatigue and tabulates the number of rubs achieved.

Whether conducted manually or by machine, this simple test is a rapid, effective way to ascertain that the required level of cure is achieved for optimal service life.

Cynthia A. Gosselin, Ph.D.,Ìęis director at The ChemQuest Group,Ìę. ·ĄłŸČčŸ±±ô:Ìęcgosselin@chemquest.com.

One of the more discussed paint adhesion and hardness tests involves “scratching” paint off a substrate. Not only does this type of testing depict a qualitative level of adhesion, but in many instances, it also provides a relative idea of degree of cure and hardness of the organic coating.

The genesis of scratch testing is found in the very old (pre-1960) National Coil Coating Testing Manual, Appendix A–Test Method NMCTP–17-92. Scratching could be preceded by environmental testing or conducted immediately after painting. The paint surface was scratched through the paint film with the edge of a nickel—hence also known as the “Nickel Adhesion Test.”

Every paint line superintendent had their favorite nickel in their pocket that, according to their experience, produced consistent results. A photographic standard was used to determine the quality of adhesion as depicted by the thickness of the paint removal line. (Figure 1) The thicker the substrate exposed within the scratch line, the poorer the adhesion. Acceptable adhesion levels were determined between the paint vendor, coated product producer, and the final customer to ensure success in the field.

FIGURE 1 Nickel adhesion photographic standard.

While the Nickel Adhesion Test provided surprisingly consistent relative results, more sophisticated and reliable quick adhesion and hardness testing was needed. In 1974, ASTM published ASTM D3363-74 Standard Test Method for Film Hardness by Pencil Test. This test method was a quick, inexpensive determination of film hardness. Relative adhesion and degree of cure could be inferred during testing. In 1980, the National Coil Coating Association issued an update of the ASTM specification as Technical Bulletin 4.2.5 (NCCA No. 11-12). The next iteration of this specification took place in June 1996 when a revised version was published in a compilation of testing for the coil coating industry. This revision was heavily influenced by the methodology utilized by ASTM.

Currently, ASTM D3363-74 (22) is an updated staple within myriad testing protocols included in ASTM Volume 06.01, routinely undergoing the rigorous five-year review process.

Pencil hardness testing involves holding a variety of flattened pencil leads of differing hardness at a 45° angle. The leads are pushed into the paint, away from the operator, using a 6.5mm (0.25″) stroke.

The process starts with the hardest pencil and continues down the hardness scale to the point where the lead will not cut into the film (hardness) or will not mar the film (scratch hardness). Any defacement of the film other than a gouge (cut) is considered a scratch. Both endpoints are reported to provide a full view of the paint film.

Calibrated pencil drawing leads or equivalent calibrated wood pencils are used. These leads meet the following hardness scale, with the difference between two adjacent leads considered as one unit of hardness.

Sometimes the point at which gouging occurs points to the relative degree of cure, which can affect hardness. High-reflectance white paint is one such product. The system required an H-pencil standard for the paint to adhere without incurring damage during the stamping process. Anything less results in paint peeling in the die, even if volume solids, paint film, color, reflectance, and crosshatch adhesion are perfect. Using the strict H-pencil criteria with mutually calibrated leads allows for the verification of enough cure to withstand the stamping process and a significant decrease in rejected material.

However, critics of this type of human/manual test are always looking for a combination adhesion/hardness test that can be perfectly calibrated and demonstrate excellent precision, repeatability, and reliability. There have been many attempts, but nothing comes close. Often alternative testing has proven too complicated and time-consuming, or it requires expensive, hard-to-calibrate equipment. That may be fine for a research laboratory, but for production labs and field evaluation, it is not practical.

To determine just how good (or bad) this test is, results of precision testing were added to the ASTM standard. A detailed interlaboratory study was conducted, analyzing data both within and between different laboratories. The study found that an interlaboratory standard deviation was 0.52 and 0.61 between laboratories. Based on this study, criteria were developed to judge the acceptability of results at a 95% confidence level. If two operators using the same panels and pencils produce results that differ by more than one pencil unit, the repeatability and reproducibility should be considered suspect.

This surprisingly good result makes pencil hardness one of the quickest and most relevant adhesion/hardness tests within the industry. Yes, it is qualitative and relative (not mathematically absolute), but good enough to provide confidence in the ultimate success of the product in the field.

Cynthia A. Gosselin, Ph.D., is director at The ChemQuest Group, www.chemquest.com. Email: cgosselin@chemquest.com.

By Cynthia A. Gosselin, Ph.D., The ChemQuest Group

This ASTM column is a bit different from previous ones that delved into testing standards and their foibles, histories, how-to instructions, and analytical results. The main theme of this writing is terminology—which, when dissected, leads to exact meaning, precise communication, and a clear understanding of the definitions assigned to various technologies and technical standards.

Each of the more than 140 ASTM Committees has an important standard in the library that is often ignored. This standard governs definitions for each subject category, and yet, it generally goes unnoticed during most Committee Weeks. Often people become aware of this standard when one of their customers questions a specific issue by quoting one of the definitions. Known as the Editorial and Terminology Standards, they are filled with technical, trade, and industry definitions of words found within the technical standards. And, as the Led Zeppelin song states— you must read carefully—“because sometimes words have two meanings.”

For example, ASTM D16 is the primary standard governing the main committee relevant to our industry, ASTM Committee D01 on Paint, Related Coatings, and Materials. This standard is the first one in Volume 06.01. However, due to the diverse and highly technical subject matter associated with paints, coatings, and materials, there are also specialized terminology standards under the jurisdiction of D01. These include:

• D804 Terminology Relating to Pine Chemicals Including Tall Oil and Related Products (Volume 06.03)
• D1695 Terminology of Cellulose and Cellulose Derivatives (Volume 06.03)
• D6440 Terminology Related to Hydrocarbon Resins (Volume 06.01)
• D6488 Terminology Relating to Print Problems (Volume 06.02)
• D7188 Terminology for Printing Inks, Materials and Processes (Volume 06.02)
• E284 Terminology of Appearance (Volume 06.01)

Each of the specialized standards augments the main Committee D01 standards. While the specialized standards may be in separate print volumes, all terms are identified in one place in the online Terminology Dictionary on the ASTM website. The main reason for the specialized standards is to further refine definitions as needed for subject specificity.

The scope description of these critical standards is that of a compilation of terminology relevant to the technical details espoused within the committee or specialized standard subject matter. These definitions identify and precisely define the words used within the context of the science being examined.

For clarity and simplicity, a definition is a prescribed single sentence that can be augmented by discussion notes as needed. However, the goal is to define a term as precisely as possible—defined with as few words as needed for a precise explanation. If a definition gets too wordy, too long, or too detailed, much of the understanding of the term is lost. In fact, a definition with more than one sentence is prohibited by the ASTM Form and Style Manual and is sure to receive a negative vote.

Even so, sometimes even the simplest definitions need a little more context. In that case, a discussion section can be added, which can be as long and as detailed as needed.

A term is included within a terminology standard only after the task group within the responsible subcommittee has reviewed it and reached the consensus that it is either a generally used term (such as in D16) or a descriptive term used in a specific technical area (such as D7188).

The process for publishing a definition begins with the term being voted on within the entire subcommittee. If it passes without any negative votes, it is then balloted again within the main committee. The main committee vote either validates the definition or returns it to the subcommittee for review and revision if there are negative votes. It is important to note that all negatives must be addressed—even those from outside the submitting committee—before final acceptance. Definitions may be identical to those published by other committees or may vary in meaning depending upon the scientific context. The terminology section on the ASTM website provides the location of definitions for every term within all the Editorial and Terminology Standards, highlighting those that have disparate or similar meanings across different technologies.

Some of the ASTM Committees have comparatively fewer Editorial and Terminology Standards than Committee D01, allowing for an easy review of all individual definitions every five years. In Committee A05 on Metallic-Coated Iron and Steel Products, each term also includes the date of original publication. This makes it quite easy to review a term every five years based on its “birthday.”  Because technology changes, manufacturing processes evolve, and steel chemistries are added and subtracted, this makes for a timely modernization of definitions. Note that this committee is also one of the smaller ones with 49 definitions with no additional specialized terminology standards and is considered an ideal case.

Others, such as the D01 Committee Standards on Paint and Coatings, have hundreds of definitions—as represented by more than 600 standards and a total of seven Editorial and Terminology Standards. In this case, practicality demands that definitions tend to be reviewed as technical standards become obsolete, or items within reviewed standards change—as the normal five-year review of hundreds of individual terms is impossible at this point.

New definitions are added as technologies emerge or if new standards contain undefined terms. Sometimes, well-known trade staples such as “pot life” were never defined within the terminology standard (or even within the standard that utilized the term). They were added well after the terms were used for decades, often when someone did a thorough five-year review of one of the associated technical standards or had an argument with a customer. As a result, these huge terminology standards often have legacy terms that have remained even though the definitions have long expired. A thorough review of the D01 Committee standard would take the work of many people with a good depth of understanding of technical standards and practices, along with quite a bit of volunteer time.

To combat the seeming invisibility of Editorial and Terminology Standards, ASTM has taken steps to enhance awareness throughout the organization.

One of those steps is a renewed focus during the prescribed five-year review of all technical standards as they come due to ensure that the Terminology Section within each committee (and thereby each standard) is robust and up to date. This was also codified in the newest ASTM Form and Style Manual. Some older working standards had completely omitted a terminology section in the past and are currently being revised accordingly.

Each standard identifies key terms, which are then incorporated into the main committee standard, lending precision to the wording in each procedure. It is helpful to precisely define the term within the context of the relevant section. More importantly, individual technical standard terminology sections should be mirrored in the Editorial and Terminology Standards. The added advantage is that this focus allows for a practical way to review even the longest list of standing definitions allowing for adjustments, deletions, and additions, hitherto relatively impossible.

Most people are excited to work on technical standards that govern testing, equipment, and scientific analysis. Unfortunately, terminology is usually a stepchild, as wordsmithery, wordplay, and precise definitions are not as “interesting” to those locked into process flow, new material development, or experimental details. Even so, standards are only as good as the words implemented, and testing is based on precisely communicating concepts, making terminology an important part of ASTM.

Full disclosure, I am the chair of both the Committee A05 and D01 Editorial and Terminology Subcommittees (Subcommittees A05.11 and D01.18, respectively) as I have always been interested in describing processes and concepts and precise definitions. We are always looking for volunteer subcommittee participants who are interested in reviewing terms and solidifying and debating the merits of old, new, or revamped definitions. This applies across the board to all 146 committees governing everything from aromatics to zinc.

If you would like to contribute your expertise to a committee, joining is easy. The ASTM website provides a seamless way to connect with the organization and select committees of interest. A nominal fee of $115 per year entitles each member to a free printed or electronic ASTM standards volume of choice, free attendance for the twice-yearly committee meetings, and unlimited networking opportunities in your field or tangential and completely different fields of interest. These are individual memberships, so you can join and represent your company or industry independently.

If you are interested in finding out more information, please feel free to email me with any questions or comments. If you are interested in joining one of the many Main Committees, and hopefully also lend your expertise to one of the Editorial and Terminology subcommittees, please . There you will find all kinds of information about membership and member resources. Looking forward to seeing you at the next Committee Week meeting.

Cynthia A. Gosselin, Ph.D, is director at The ChemQuest Group/ChemQuest Technology Institute/ChemQuest Powder Coating Research;Ìęcgosselin@chemquest.com;Ìę.

Color is the most critical and obvious coating attribute because it is essential to match both large industrial batches and small one-gallon cans of DIY paint, ensuring the final product is visually consistent for everyone. The question arises whether color perceived by the human eye or quantitative machine “true” color is better. An entire science of color measurement has developed over time to answer this question.

Perceived color measurements, known as Specular Component Excluded (SCE), excludes the specular component (dominant type of reflection) to make the result more sensitive to scattered light caused by surface conditions such as texture and gloss. True color measurement, called Specular Component Included (SCI), captures all reflected light irrespective of the reflection—specular, diffuse, or scattered angle. SCE is the best way to verify true color during production, while appearance perception (i.e., metamerism, brightness) is best quantified with SCI.

Surface finish has a profound effect on color perception. The same true color on a high-gloss surface (≄70 GU) will appear to the eye more saturated and a semigloss surface (20-27 GU) will appear less saturated due to a decreasing spectral component of reflected light. A matte finish (<20 GU) will appear dull. As a result, most paint quality control and product parameters specify both gloss and color simultaneously.

ASTM addresses color measurement parameters through a series of 16 standards. The parameters used within all but two standards are based on the CIE (Commission Internationale de l’Éclairage) system of tristimulus color measurement applied worldwide when measuring color. This system makes color measurements universally clear and globally meaningful. Table 1 lists ASTM standards available for color matching most paints and coatings.

Most color-measurement standards include definition of the following parameters: Color scale, CIE illuminant (defined white point, usually E D50 or D65 in color space diagrams), CIE Standard Observer (the 1964 10 Degree Supplementary Standard Observer represents most closely how the human eye perceives color), instrument geometry and mode, sample preparation, and sample presentation.

The L∗a∗b∗ technique mathematically defines color with a measurement instrument. The letters represent each of the three values the CIE L∗a∗b∗ color space uses to measure objective color and calculate color differences. L∗ represents lightness from black to white on a scale of zero to 100, while a∗ and b∗ represent chromaticity between the color produced and the standard, with no specific numeric limits. Color difference is the numerical comparison of a sample color to the standard. It indicates the differences in absolute color coordinates and is referred to as Delta (Δ). The overall differences, are defined as ΔE and calculated as follows:

This formula calculates the specific differences between two colors to assist in quality control as illustrated in the L∗a∗b∗ color sphere and calculation coordinates (Figure 1).

FIGURE 1 L∗a∗b∗ color sphere and calculation coordinates.¹

Two types of instruments measure paint color. Colorimeters see color like a human eye and can determine a location in color space by using values of tristimulus red, green, and blue and determining each color location with L∗a∗b∗ metrics. Spectrophotometers provide a more accurate measurement of color across the visible spectrum and filter light through narrow bands of color between 300 and 700 nanometers. These bands pass through instrument optics and receivers for recording as a unique reflectance band fingerprint for that sample. The latter is the best way to develop formulations, as it is more apt to eliminate most color-matching errors.²

The Gardner Color Scale measures the color of transparent liquids such as oils, varnishes lacquers, fatty acids, lecithin, sunflower, and linseed oil. It is a strictly visual one-dimensional, single-number analysis that is either manual (ASTM D1544) or instrumented (ASTM D6166).

As presented in Table 1, established ASTM methods universally identify, compare, and set color parameters, ensuring consistency and reliability, whether using precise machine measurements or the human eye.

Cynthia A. Gosselin, Ph.D, is director at The ChemQuest Group/ChemQuest Technology Institute/ChemQuest Powder Coating Research;Ìęcgosselin@chemquest.com;Ìę.

References

1. Saju, Abhijut K. Understanding Solor Space and Delta E. Havells India, Ltd. LinkedIn. 2023. https://www.linkedin.com/posts/abhijeetksahu_linkedin-community-colorscience-deltae-activity-7088421572566249472-ruPT/ (accessed July 31, 2024).
2. X-Rite PantoneÂź Color Blog. Color Measurement Devices. X-Rite Color. June 19, 2022. https://www.xrite.com/blog/color-measurement-devices (accessed July 31, 2024).

The concepts of viscosity and rheology are often confused, even though they are significantly different. For this discussion, rheology is the study of the flow and deformation of liquids (paints and varnishes) under applied forces. Rheology includes viscosity, elasticity, and plasticity. Viscosity, on the other hand, is defined specifically as a measure of resistance to deformation under shear stress and is the most common rheological measurement of a paint system. Viscosity is often likened to the “thickness” of a fluid. In short, rheology is the broad study of how materials flow and deform, while viscosity is a more specific property related to a resistance to flow.

Viscosity is one of the defining properties of commercial paint systems and is always listed on a technical data sheet to ensure quality control and performance. Viscosity can be calculated but is generally best measured directly. Equipment ranges from the simple Ford Cup, which measures one flow time at a single rate, to the digitized viscometers that are set up to measure a variety of flow rates quickly.

When measuring viscosity, it is important to understand whether the fluid is Newtonian or non-Newtonian. The viscosity of Newtonian systems is constant and independent of shear rate. Non-Newtonian fluid viscosity is dependent on shear rate and changes accordingly. Paints, inks, and varnishes usually fall into the non-Newtonian category, while oils and lubricants tend to be Newtonian.

For example, one non-Newtonian behavior is shear thinning, where the liquid becomes less viscous when shear (mixing) is applied, as occurs during application. When the shear is removed, the liquid regains viscosity. This is a desirable attribute for many paint applications so that the paint can be easily applied but then does not drip or sag after application.

There are nine ASTM standards commonly used for measuring the viscosity of paint systems. Each standard measures viscosity at the point of approximating the paint application process. The standards are governed by two subcommittees in ASTM Committee D01 on Paint and Related Coatings, Materials and Applications. The most widely used standards include:

• ASTM D1200 Standard Test Method for Viscosity by Ford Viscosity Cup
• ASTM D1823 Standard Test Method for Apparent Viscosity of Plastisols and Organosols at High Shear Rates by Extrusion Viscometer
• ASTM D1824 Standard Test Method for Apparent Viscosity of Plastisols and Organosols at Low Shear Rates
• ASTM D2196 Standard Test Methods for Rheological Properties of Non-Newtonian Materials by Rotational Viscometer
• ASTM D4212 Standard Test Method for Viscosity by Dip-Type Viscosity Cups
• ASTM D4287 Standard Test Method for High-Shear Viscosity Using a Cone/Plate Viscometer
• ASTM D5478 Standard Test Methods for Viscosity of Materials by a Falling Needle Viscometer
• ASTM D7395 Standard Test Method for Cone/Plate Viscosity at a 500 s-1 Shear Rate
• ASTM D7867 Standard Test Methods for Measurement of the Rotational Viscosity of Paints, Inks and Related Liquid Materials as a Function of Temperature

With the variety of viscosity measurement standards available, it is possible to select techniques to determine viscosity parameters for product families, application methods, or overall behavior at different temperatures and/or shear rates. Table 1 provides a guide to the type of viscosity measurements governed by each standard, along with the significance of those measurements to application parameters or to viscosity behavior at various temperatures or shear rates.

ASTM viscosity testing can be used to analyze either general paint characteristics or fluid conditions at certain steps in the painting process. The variety of tests available ensure that viscosity parameters can be measured as a simple quality control operation or as a defining characteristic of the paint system. Using the correct test enhances the quality of the overall process.

Cynthia A. Gosselin, Ph.D, is director at The ChemQuest Group/ChemQuest Technology Institute/ChemQuest Powder Coating Research;Ìęcgosselin@chemquest.com;Ìę.

Confocal microscopes are useful research tools for spatial characterization of heterogeneous coating systems. In a confocal microscope, emitted, reflected, or scattered light from the sample is detected through a spatial pinhole, which blocks most of the out-of-focus lights to enhance depth resolution and image quality. The depth profiling feature essentially enables optical sectioning of samples without destructive sample preparation, like cross-section microtoming. The article described three illustrative applications of confocal Raman microscopy (CRM) and confocal laser scanning microscopy (CLSM) to investigate some common coatings phenomena.

Quantification of Component Distribution Using Raman Intensity Ratio
In Example 1, lateral and depth mapping of a styrenated additive was performed by comparing the intensities of Raman transitions associated with phenyl ring of the additive with that of the carbonyl groups of the acrylic polymer. In pigmented coatings, titanium dioxide (TiO2) is a strong absorber at low wavenumbers, and film opacity causes depth attenuation of spectral intensities. By focusing on the spectral range for organic components, the authors monitored the intensity ratios of styrene to acrylic signature bands at various depths to minimize the influence of signal attenuation. As a result, spatial analysis of the additive present at only 2 wt % in the pigmented acrylic paint formulation was determined (semi)quantitatively. The additive concentration, reflected by a constant intensity ratio throughout the film, confirmed its uniform distribution in non-transparent, pigmented coatings.

Visualization and Quantification Using CLSM

Figure 1—Fluorescence images of acrylic polymer film (blue) stained by grape juice (pink).

Compared with CRM, CLSM using reflection or fluorescence contrast can provide real-time 3D imaging with greatly improved speed and spatial resolution. An example is shown in Figure 1 (Figure 9 in the original article), which depicts layer-by-layer optical sectioning of latex film stained by grape juice. The intrinsically fluorescent color compounds in the grape juice provided distinct microscopic contrast and spatial differentiation in the color-coded spectral images. CLSM therefore enabled direct visualization and quantification of stain penetration in the polymer matrix.

(Semi)quantitative Analysis Through Novel Data Processing Methods

Figure 2—CRM data on effect of staining time.

When standard peak-fitting or intensity ratio calculation is not possible, special data processing techniques are required to extend the use of CRM for quantitative and semi-quantitative analyses. In Example 2, the authors explored the second derivative analysis of Raman spectra to resolve low concentration of a surfactant leached out on the film surface of a semi-gloss white paint. In Example 3, a novel data analysis method was developed to take advantage of the fluorescence emission of grape juice. Fluorescence is generally an unwanted limitation encountered often in Raman spectroscopy. The area ratio of the fluorescence envelope to the C-H region was exploited to characterize adsorption, penetration, and removal of grape juice stains. Figure 2 (Figure 16a in the original article) illustrates a typical example of CRM extracted data. The intensity ratio at zero depth was related to the surface concentration of grape juice. The minimum in the depth profile plot was taken as the end point of grape juice penetration. Using this approach, effects of different binder polymers, staining time, and washing protocols were investigated. The CRM semi-quantitative analysis yielded excellent agreement with color measurements from the empirical washability test, while providing deeper insight into the staining and stain removal processes.

In summary, the article demonstrated that confocal microscopes can be employed to skillfully map spatial locations of various chemical species even in pigmented, multi-component coating systems.

Wenjun Wu, Arkema, Inc., Arkema Coating Resins. ·ĄłŸČčŸ±±ô:Ìęwenjun.wu@arkema.com. Dana Garcia, Arkema, Inc. Jeffrey Schneider, Arkema, Inc., Arkema Coating Resins. 

By Jessica Lum, Madeline Schultz, and Erik Sapper, Department of Chemistry and Biochemistry, California Polytechnic State University

identification, measurement, and reduction of volatile organic compounds (VOCs) has been a key motivator in recent coatings research and development efforts. Analytical methods for determining VOC levels in organic coatings continue to improve, as chromatographic and spectroscopic approaches afford a means of quantifying VOC content directly in waterborne as well as solventborne coatings.

Heuristic methods for estimating the volatility of formulation components are common but are not extensively validated using quantitative structure-property relationships. Thus, a clearer link between component transport through an evolving coating matrix during curing processes, the bulk volatility of a compound, and the elution and quantification of compounds in a gas chromatograph (GC) still must be made to promote innovation in this area.

To address these issues, digital tools such as molecular descriptors and machine learning models are being combined with experimental measurements to better understand the time-dependent mechanistic nature of VOCs in coatings and to enable predictive control over the volatility and in-coating behavior of newly developed formulation components.

Here, we present the development and validation of a molecular structure-based neural network for the prediction of response factor for formulation components in a gas chromatography (GC) analysis. This represents an important step in creating large-scale computational design tools that enable in silico formulation, optimization, and end-use property prediction of environmentally benign coatings.

INTRODUCTION

Consumer and market demand within the coatings industry continues to put pressure on formulators to create high-performance coatings that also have adequately low levels of volatile organic compounds. An ongoing challenge is the creation and optimization of important end-use coating properties while still meeting environmental regulation specifications.

As formulators are urged to innovate more quickly, it has become apparent that traditional empirical and Edisonian (guess-and-test) methods, even statistically designed methods of formulation discovery, must be augmented with newer technologies, such as those represented by digitization, automation, machine learning, and artificial intelligence.

There is also an increased emphasis on understanding chemical and physical interactions within the formulation at all stages of the paint production, application, and film-forming process. The growing consumer demand for environmentally benign “green” coatings has led to a push within the paint industry for improved predictive models and developmental workflows that make use of these next generation technologies.

Consider, for example, the recent South Coast Air Quality Management District (SCAQMD) Test Method 319 (Determination of Exclusion Status for Compounds in Film-Forming Coatings), where measurement, estimation, or prediction of the low vapor pressure of a formulation component may lead to its exclusion in VOC calculation and reporting.

Environmentally conscious consumers and regulatory agencies such as the U.S. Environmental Protection Agency (EPA) have continued to drive the paint and coatings industry towards greener formulating methods, such as shifting from solvent-based to water-based coatings as a method of reducing VOCs.

Throughout the late 1960s and 1970s, there was an increased concern regarding air pollution and the detrimental effects to both human and environmental health.

From this pollution arose the need to define and regulate the effect of paints and coatings on the local environment by limiting the amount of certain additives in paint which are damaging to the environment.

The EPA identified volatile organic compounds as “any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions, except those designated by the EPA as having negligible photochemical reactivity.”¹

The EPA calculates compliance with VOC content regulations (Title 40, Chapter I, Subchapter C, Part 59, Subpart D—National Volatile Organic Compound Emission Standards for Architectural Coatings S: 63 FR 48877, Sept. 11, 1998, §59.406) according to Equation 1:

In Equation 1, VOC content = grams of VOC per liter of coating; W_v = mass of total volatiles, in grams; W_w = mass of water, in grams; W_ec = mass of exempt compounds, in grams; V = volume of coating, in liters; V_w = volume of water, in liters; and V_ec = volume of exempt compounds, in liters.

In 1984, the EPA introduced Method 24 to quantify the amount of VOCs in coatings and inks sold in the United States. Method 24 is an indirect method of VOC determination, wherein the water content, solids content, and density of the coating are directly measured and used to back-calculate the amount of VOCs by a mass difference approach.

Method 24 is insufficient for waterborne coatings with low VOC content, as the indirect method erroneously determines small mass fractions of VOCs as compared to the much larger water weight percent, with exponentially increasing error below VOC content of approximately 250 g/L.

As coatings shifted from solvent-based formulations to more environmentally friendly water-based formulations, the insufficiencies in this method motivated the need for new standardized regulatory methods and measurement procedures. Despite the need for improved methods, EPA Method 24 is currently the regulatory method federally mandated across the United States.

States and regions throughout the United States have various guidelines that extend beyond federal rules. California, particularly the Los Angeles air basin, has faced, and continues to face, high prevalence of air pollution known as “smog,” a portmanteau coined in the 1900s to describe the uniquely industrial mixture of smoke and fog becoming increasingly prevalent in large urban areas.

Regulatory agencies such as the California Air Resource Board (CARB), and more specifically SCAQMD, formed the most stringent regulations in the United States to reduce the local effects of this increasing pollution. Method 313 is a direct method for the measurement and quantitation of VOCs using a gas chromatograph with flame ionization detector (GC-FID) applied to samples with less than 150g/L of VOCs.

The complexity of this method is the main deterrent to its use. VOCs are quantified via multilevel calibration curves generated for each analyte used in the coating formulation.² Relative response factors allow for the calculation of volatiles through this direct method. The regulation of VOCs is relative to the retention time of methyl palmitate. Compounds that elute prior to methyl palmitate are not included in the calculation of volatiles per liter coating. The complexity and laborious sample preparation associated with this method render its use undesirable and drove the innovation of a new standard: ASTM D6886.

ASTM D6886 is a non-regulatory analytical method suitable for the analysis of coatings with less than 150g/L of VOCs, which resulted from an in-depth study by California Polytechnic State University for the California Air Resource Board.³ This method does not define a VOC as Method 313 does, rather it identifies and quantifies all volatiles within a formulation. Although it is not regulatory in nature, it has been widely adopted by SCAQMD as it provides for a less labor-intensive direct measurement of VOC content in coatings as compared to Method 313.

Like Method 313, GC-FID is used in ADTM D6886 to quantify the volatile compounds present in the material. This method utilizes an internal standard, ethylene glycol diethyl ether (EGDE), for the calculation of response factors for an analyte of interest, as discussed in subsequent sections of this manuscript. Herein all response factors discussed were collected according to ASTM D6886.

Globally, VOCs are regulated by federal and local governments. Looking beyond the United States, Europe developed ISO 11890, a widely employed direct method for the analysis of samples with expected VOC content between 0.1% and 15% by mass.⁴

While Method 313 defines a VOC as anything that elutes before methyl palmitate, ISO 11890 defines a VOC as compounds with a boiling point below 250 °C. This is dictated by EU Directive 2004/42/EU.⁴ ASTM-D6886 and ISO 11890 are very similar in practice, with direct measurements preformed via GC-FID, and primarily differ in the associated VOC determination that follows as dictated by regulatory agencies within relevant regions.

Here, we combine structure-property relationships, neural networks, and gas chromatographic analytical methods to create a digitally enabled workflow that can support the formulator chemist while evolving as quickly as the regulations themselves.

We present a multipronged approach to working with, measuring, and understanding the nature of VOCs in coatings formulations. First, we present a method of improved prediction for quantifying the response factor (RF) of compounds being analyzed by gas chromatography, as a means of augmenting and expediting VOC determination by ASTM D6886 and other chromatographic approaches.

Ongoing work is employing vapor pressure (VP) prediction and measurement to improve the working definition of VOC as it applies to coating production, application, and film-formation processes. Finally, we propose new directions for incorporating these predictive approaches into the formulation development process.

This article will walk through the first and often the most complex part of a robotic application setup process, explain practical techniques, define some basic process acceptance criteria, and define typical terminology used by some of the industry’s most capable paint application specialists.

Adding a painting robot to a production process can bring with it improved quality and productivity. The functionality and cost of robotic paint systems has improved tremendously over the past two decades, and the technology is earning its way into small and medium-size production operations.

Coating systems bring tremendous value in decorative application and functionality to products. At the same time, the industry goes to great lengths to minimize or eliminate human exposure to overspray and solvent vapors.

For repetitive coating processes, a robot can be a great way to minimize human exposure, provide a stable and uniform film across months and years of production, and maximize production throughput. It is not difficult to program a robot to move along a path at a given speed and trigger a paint applicator nor is it difficult for a human to wave their arms and trigger a spray gun. Knowing how to properly configure the applicator, coordinate triggers and motions, and manage process variables is what separates a highly skilled painter from an unskilled sprayer.

There can be a dozen or more interrelated factors at play during a coating application process. What seems simple on the surface has left many capable engineers and chemists wringing their hands in frustration while spraying hundreds or even thousands of test panels to find optimal application settings for their robotic application process.

A trial-and-error setup approach is expensive, time consuming, and frustrating for everyone involved. Fortunately, there is a very successful and time-tested structured methodology employed by many of the coating industry’s most capable users, applicator manufacturers, robot manufacturers, and material formulators.

With a data-driven and structured approach, any organization with a robot and a paint applicator can leverage these techniques to greatly reduce the time and effort required to set up a high-quality robotic painting process. There is a wealth of technical literature available on paint atomization, coating formulation, and robotic optimization.

A person new to this rapidly growing field of automated paint application may find themselves overwhelmed with data or may not realize that they are reinventing wheels that were perfected long ago.

This article will walk through the first and often the most complex part of a robotic application setup process, explain practical techniques, define some basic process acceptance criteria, and define typical terminology used by some of the industry’s most capable paint application specialists.

APPLICATION PROCESS OVERVIEW

A successful robotic paint application plan is rooted in well-informed choices, trials and tests that revise or confirm those choices, and an approach that successively builds complex processes with confirmed data. It is nearly impossible to “guess and check” robot path and applicator parameters that will result in a stable quality coating without wasting significant time and material.

Another approach often doomed to failure involves creating an “efficient” path for the robot and then attempting, usually for weeks or months, to find applicator parameters that meet the requirements of the robot path. An analogy of trying to install the roof of a house before the foundation is poured comes to mind. A systematic setup process can be performed on relatively inexpensive metal coupons and masking paper that will save a tremendous amount of time, expense, rework, and headaches.

The steps outlined in Figure 1 illustrate the process. Avoid the urge to skip steps in the interest of time, money, or professional ego. If the assumptions are correct, the test will be quick, easy, and use minimal resources. If the assumption is incorrect and not realized at the proper stage, all the downstream steps will be wasted effort and will need to be repeated. Each of these tasks will be described with the general criteria for acceptance before moving on to the next step.

In the paint and coatings industry, a variety of external resources are available to assist an organization when it finds itself missing the necessary equipment, expertise, or time to address needs and opportunities.

Whether it is developing a new technology, validating performance of a new product, or investigating how to participate in a new market segment, even the largest of organizations have the occasional need for outside support. The external resources available include business and technical consultants, toll and private label manufacturers, academic and government institutions, and independent laboratories.

Third-party, independent commercial laboratories are like other vendors in that they provide a service or goods for payment but are unique because their service is supplementing the client’s own research and development activities and capabilities through experimental work.

Independent labs in the paint and coatings market may choose to offer a variety of services, which could include R&D targeted at the development of new raw materials or coatings, formulation optimization, performance testing, analytical testing, reverse engineering, failure analysis, and accelerated and natural weathering.

Not having the right knowledge and expertise in-house is sometimes a reason for seeking out an independent laboratory. The choice of a suitable laboratory as partner can afford an organization with that expertise, without the need to hire an additional employee. New equipment can be very expensive and might require personnel with special expertise to operate, and thus might not make sense to purchase and bring in-house, especially if it would be used infrequently. Here again, choosing the appropriate lab can allow access to certain equipment and testing without the capital expense.

Sometimes, an organization may have maxed out on their own resources, whether it be personnel to carry out formulating and testing, or space in a popular piece of equipment. An independent lab can assist in expanding a company’s R&D resources.

There are many benefits to seeking the assistance of a third-party, independent laboratory, and they fill an important function in our industry. CoatingsTech reached out to several laboratories to hear their perspectives on their unique role in the paint and coatings industry, why clients seek them out, and how they assist industry members in their research and development efforts. In addition, they dispel some common misconceptions about third-party labs and discuss tips for ensuring a successful partnership with an independent laboratory.

Participants in the discussion included: James E. Swope, chief commercial officer at The ChemQuest Group; Matthew McGreer, director at Atlas Weathering Services Group; Dan Marschall, president of Marschall Labs; Michael Crewdson, technical director of testing services at Q-Lab Test Services; Paul Lewis, technical manager at Univar Solutions; Ronald Obie, president of Wood Coatings Research Group; Robert Leggat, consulting and laboratory services manager at KTA Tator; Gerald Vandezande, president of 1st Source Research; Edye Fox Abrams, vice president of business development at The ChemQuest Group; and Mike Dempsey, marketing and business development at 1st Source Research.

Independent Laboratories Q&A

Answers may have been edited for clarity and length.

Q. What is the role of independent laboratories in the R&D process?

Swope, The ChemQuest Group: Multiple roles are possible. These include helping a customer in accelerating timelines to hit an aggressive deliverable and breaking a creative logjam similar to writer’s block. Other roles include characterizing new raw materials, including nano- and bioderived materials, and providing independent data either as a check on the inventor’s data or as data beyond in-house capabilities. Depending on where one is positioned in the coatings value chain, the role of our ChemQuest Technology Institute and ChemQuest Powder Coating Research labs can differ greatly. At the end of the day, our role is to help expedite product knowledge and commercialization activities.

McGreer, Atlas Weathering Services Group: The independent lab’s role depends on what the research question is. For example, is the client looking for a customized testing solution to predict service life? Are they looking to meet a material specification? Are they testing a minor revision to their product’s formulation? Each of these questions would require a different type of support from the lab. This could include consultative support, advising on an appropriate existing testing method, or simply running a common method that would be considered “spec testing.”

Marschall, Marschall Labs: The ideal outcome of a collaboration between a client and independent laboratory should be a purely unprejudiced scientific investigation that contributes to validating the performance versus cost of the finished product.

Crewdson, Q-Lab Test Services: The two main roles of independent weathering and corrosion test labs in the R&D process are the confirmation that the manufacturer’s labs have their preliminary data correct and the ability to run more complex and newer tests. Independent labs generally have the newer and more reliable test equipment, and the expertise to run them correctly. Independent labs run a much wider variety of tests, and will be accredited for them. This means that calibrations, maintenance, and training will all be at a high level.

Lewis, Univar Solutions: When coatings companies are looking to develop new products or upgrade existing products, they often do not have the expertise, test equipment, starting point formulas or other resources they need. Independent laboratories like Univar Solutions’ Solution Centers in the United States, Latin America, and Europe have experienced coatings formulators and application specialists with deep expertise and performance testing capabilities. This helps companies get to market faster.

Obie, Wood Coatings Research Group: Independent laboratories provide technology assessment and qualification through an unbiased lens. Independent laboratories can also often provide insight as to where a new technology may actually bring value, that often may not have been the original intention of the product development process.

Leggat, KTA Tator: One role of the independent laboratory is to provide independent results, which can be an advantage for both marketing and legal purposes. Also, an external verification at milestone decision points is useful before investing in scale-up and commercialization. Sometimes, independent labs can offer swing capacity, for example for customers whose in-house resources are currently tied up. Also, they can provide access to specialized equipment.

Vandezande, 1^st Source Research: The role of an independent lab varies depending upon the needs of a customer. An independent lab could be engaged at the starting point of a project, somewhere in the middle of a project, or after a project has failed and there is a need for external expertise. There can be many roles that an independent lab performs in the R&D process ranging from analytical and testing to new product development and product formulation. At 1st Source Research, we partner with customers to understand their stated needs and then conduct the appropriate work they have hired us to complete. While some independent laboratories serve a narrow focus conducting a variety of ASTM tests and providing analytical testing services, we are a little unique at 1st Source. We tend to be viewed by our customers as an extension of their R&D, marketing, and production departments, and therefore play a vital collaborative role in the growth of the customers’ company.

Q. Why do members of the paint and coatings industry seek out the help of an independent lab? What benefits can they expect?

Leggat, KTA Tator: Third-party laboratories such as KTA Tator can help in understanding and performing the testing techniques that are used in different markets. Clients can expect a different and broader perspective on various market segments and substrates.

Obie, Wood Coatings Research Group: Independent laboratories provide an objective, unbiased assessment of technology, and/or proposed ideas. Independent laboratories also provide creative and unique perspectives regarding research, development, and technology assessment. In some cases, a customer may not know or understand some of the “finer detail” requirements for a product to be successful in a given market. An independent laboratory may be able to assist with this. In other cases, a customer may not be able to fully understand the potential benefits a given technology may bring to a market or even to what market a new material might bring value. The creative capability of an independent laboratory can often “see” where a product may fit and provide value to the market, essentially helping the customer focus research and marketing efforts as well as improve product introduction into the marketplace.

Vandezande, 1^st Source Research: Customers in the industry seek us out for work that they cannot do internally, work they cannot get done due to other internal priorities, or simply if they need an external resource to offer some expertise from a company that has worked across a wider array of projects. They look to us at 1st Source for assistance with new product development, product formulation, and key insights through analytical and testing efforts. It is also important to add that customers find that using an independent lab can reduce overhead in R&D and marketing when investigating new markets.

Swope, The ChemQuest Group: At ChemQuest, we stress the knowledge component. We don’t just test properties, we recommend approaches and supporting tests that will speak to intended markets. Each market has its own set of needs, trends, drivers, and associated terminology and of course, testing protocols. The resulting output will demonstrate the suitability of the product for the intended markets.

We also service raw materials suppliers with starting point formulation, comparative testing, and formulary cost impact studies that help them determine where they might fit in the value chain and helps their customers/formulators with a head start evaluating the new raw material.

Marschall, Marschall Labs: We believe the majority of our clients find our services beneficial because of the quality of our unbiased work, as well as our ability to adapt to help solve any problem that might arise during testing. While most mid-to-large scale clients have their own in-house QA/benchmarking lab, what sets us apart, for example, is the ability to engineer custom machinery and proprietary image processing software so that we can derive objective results. Therefore, clients can expect an in-depth informative process that is ultimately more efficient and unbiased than traditional in-house benchmarking labs.

Lewis, Univar Solutions: We find there are three things that coatings companies are looking for in an independent lab: formulation assistance, testing, and analytical capability. In many cases, they can expect the independent lab to carry out these functions quicker and less expensively than if they did the work themselves.

McGreer, Atlas Weathering Services Group: Our lab focuses on the weathering of materials. While durability to the outside environment is an important part of any product development effort, our client may not necessarily be experienced on all the different testing methods that are available, or how to correctly set up those tests. Weathering seems like an easy discipline, but it is not always an exact science and there are still a lot of complicated questions that must be answered.

Crewdson, Q-Lab Test Services: Using an independent accredited test lab ensures that the test is done correctly. When a new product is being tested, there might not be the usual set of control materials that are used to verify the testing results. There is a much greater need to make sure the testing is done correctly. Another factor is that a company’s internal labs are often at capacity in their weathering and corrosion chambers with important but routine tests. This makes it difficult to conduct much experimentation with new methods or run a new product through several different methods. An independent lab can suggest alternative approaches to testing and run the tests.

Q. What are the most common services requested by your customers to assist in their innovation process?

Lewis, Univar Solutions: Because the Univar Solutions labs have extensive experience and lab equipment, we find it is a fairly even split between running tests, developing new formulas, evaluation of raw materials in specific applications, and carrying out reverse engineering. We have most of the test equipment needed in a modern coatings lab. We also have adhesives, sealants, and elastomers test and formulation capability.

Marschall, Marschall Labs: Product benchmarking is the most common function at Marschall Labs. More than 1,500 paints are tested annually for both interior, exterior and specialty applications. Exterior systems are also generally placed on exterior exposure for durability. We also provide a service for raw material suppliers by giving them an independent evaluation of their products.

Crewdson, Q-Lab Test Services: Our testing is aimed at answering the question, “How long will your product last outdoors?” We expose specimens to accelerated weathering and corrosion environments, which could also be outdoors in benchmark climates such as Florida and Arizona. We perform inspections, evaluations, and measurements to quantify the degradation changes and issue reports to our customers. Our most common services are visual evaluations, gloss readings, and instrumental color measurements.

Obie, Wood Coatings Research Group: Independent laboratories are typically involved in activities such as material property characterization, technology assessment, screening, testing, and benchmarking. From this standpoint, the goal is often the qualification of a product for a given market segment, identification of potential value and/or identification of potential market application(s). Also, there is new technology development such as raw materials for the coatings industry, coatings formulation development, and failure analysis.

McGreer, Atlas Weathering Services Group: For us, there really is not a “most common” service since we really focus on one thing, the weathering of materials. We are in sort of a niche business, doing strictly weathering/lightfastness testing and some of the related evaluations that come with it.

Fox Abrams, The ChemQuest Group: Materials characterization, defined as performance testing in different formulary conditions to understand a material’s benefits and disadvantages versus other materials. Another way to say this is to characterize how something works in combination with other materials, to gain an understanding of its benefits in use. Because our services are used for every conceivable coatings market, it’s hard to call anything we do “common.”

Mike Dempsey, 1^st Source Research: We have a wide range of customers in very diverse industries, and on any given day could be working on projects such as developing a new high performance polyurethane resin and coating formulation for maintenance or marine applications, or a light industrial PUD or WB epoxy product for commercial coatings. We might also formulate a new architectural paint and develop a latex for a caulking application. The scope of work is typically centered around a broad range of new product development projects and new product formulations that also require a suite of analytical and testing services. Customers also request our individual analytical services to meet their analytical needs.

Leggat, KTA Tator: Performance testing for specific environments is a common request, such as cyclic salt fog testing for atmospheric exposure, severe wastewater analysis testing (SWAT) for wastewater applications, and autoclave and Atlas cell testing for oil and gas applications. Customers also request customized tests to differentiate their product from their competitors’ products. For example, several years ago a client had a coating for buried pipe. The advantage of their product was that the excavated area could be backfilled with rock within minutes of coating application. They wanted us to develop a method to test that property and compare their product to the leading products in that market. Another common request is to facilitate field demonstrations or “take the laboratory into the field” with equipment such as gloss meters and field microscopes, and sampling for lab analysis.

Q. What are the types of questions that your clients ask you to solve?

McGreer, Atlas Weathering Services Group: For us, it is all about making sure that the specific type of weathering testing that we’re doing is the right one for the material’s final end-use application. Since many clients are new to weathering, educating them about their options is our most common form of communication.

Leggat, KTA Tator: Sometimes clients have a product that has a specific property that they think would be beneficial in a paint or coating and want to know what tests should be run to validate it.

Lewis, Univar Solutions: They often want to know what ingredients are in their competitors’ products, so we carry out analysis using a variety of techniques, such as FTIR, GC, HPLC, GPC, DSC, or TGA.

We have done projects for raw material suppliers who invent new molecules or products and have us test how they can be used in coatings formulas. This includes pigments, surfactants, plasticizers, resins and other materials. Because we have a large, spacious lab with a sizable amount of lab equipment we have even rented out our lab and had companies send their technical people to work here. This has been done on a short-term (hours) or long-term (months) basis. Sometimes coatings companies want accelerated weathering or corrosion resistance carried out as they don’t have the test equipment.

Vandezande, 1^st Source Research: The really tough ones. No kidding! For example, we have helped an organization develop a set of latexes and formulate them into a useful product portfolio. We have also helped that company build a latex plant to make those products, all within a short period of time.

With our background and range of skills, we are constantly entertaining all kinds of questions and requests from current and prospective customers.

Here is a small sample of just a few:

• How can I improve my product to perform in extreme conditions?
• We don’t know what to do with a certain material and don’t understand this market space. Can you help us?
• We have a new raw material. We need assistance in understanding where it might fit, and testing it in those markets?
• TiO₂costs are soaring. What effective methods can we use to reduce formulation costs?
• How do we make our product more environmentally friendly by incorporating bio-based materials?
• How do I increase the molecular weight of my product?
• Can you develop a polymer for us that will improve our product performance?
• Can you develop new small molecule additive chemistries that will allow us to improve our resin formulation performance?

1st Source’s business model is unique, and it would be hard to boil it down to a few questions. They are dependent upon the individual customer, the market category, as well as other circumstances. And of course, there are a variety of questions that tend to range from simple to complex, and an independent lab should be staffed and equipped to address them all.

Crewdson, Q-Lab Test Services: The number one question we are asked is “how many hours in this accelerated test does it take to equal one year outdoors?” When we run an accelerated test, our customers want to know how that relates to the natural exposures. While there is no single factor that relates time in a test to time in the real world, we can offer a lot of ways that we can derive the acceleration rate for a specific comparison. We can greatly reduce the risk of using accelerated test results to predict the actual durability of a product.

Swope, The ChemQuest Group: Usually, we help our clients identify the questions they need answered. By this I mean, we are not a typical lab who performs routine testing services. Instead, our clients are often removed from the end-use markets their materials are being evaluated for, so they rely on us to help scope an appropriate and affordable customized approach from which they can gain knowledge that applies to their market. In addition to what we already mentioned, we would add trouble shooting to the list. Troubleshooting can be at the formulation stage and involve issues such as the removal of materials of concern from old formulas, formulary processes, and analyzing application issues at point of use.

Marschall, Marschall Labs: The main questions recently are related to finding or supplying offsets for raw materials because of the current supply chain crisis.

Obie, Wood Coatings Research Group: Common questions fielded by independent laboratories often revolve around failure modes that customers are seeing with their coatings, such as why is my finish cracking, lifting, delaminating, failing? Other questions focus on areas such as determining product/technology value and performance. Still other questions revolve around new product/technology development needs.

Q. What are the key challenges that an independent lab must navigate when conducting research for a customer (e.g., IP, project scope, timing, confidentiality concerns, trust, cost, etc.)?

Vandezande, 1^st Source Research: 1st Source is composed of people who have worked for many years with several multinational corporations and is equipped to reduce the complexity of the many challenges that arise. The primary aim is to fully understand the scope of the project and the relevant deliverables. You might think that is assumed, but many companies can struggle with defining them to an independent lab. Once we are past that hurdle, the key challenge is communication. Since we are an external resource, it is critical to embed excellent communication routines with our customer to ensure we are all on the same page in all phases of the project.

Swope, The ChemQuest Group: Our biggest issue is handled right up front and that is who owns the IP. If you pay for the work, you own the IP. The next challenge is constructing a scope of work that makes sense chronologically and fits within budget constraints. Not exactly hard but the most involved part of the process. We have a strong reputation in the industry, so trust and confidentiality are not barriers, and we act like everything is covered by NDA because it usually is.

Marschall, Marschall Labs: All are important. It is important that the company knows the capabilities of the laboratory and the people working there. Marschall Labs, founded in 1991, has a staff of second and third generation employees of the coatings industry. Some of our greatest challenges stem from the diversity of our work and customers’ expectations. Time management and resource allocation is one of our greatest challenges when various concurrent projects require significantly different approaches. We are able to overcome this with our unique workforce made up of seven family members each bringing their own expertise to our organization.

Lewis, Univar Solutions: We have a strict confidentiality policy and do not discuss any customer’s work with anyone else. However, some customers understandably want their technology protected by legal documents and it can sometimes take a while for the lawyers to agree on contract verbiage. Some companies know they need help but don’t know exactly what they want us to do. We have initial no-charge consultations with them to discuss the details of their need and turn that into a lab project that will help answer their questions and address their problems. Cost is rarely an issue as our lab services are very reasonably priced.

Obie, Wood Coatings Research Group: Independent laboratories must be able to navigate all those mentioned, plus more. The key to all of them is honest, open communication regarding a given project. IP and confidentiality are usually taken care of upfront before project initiation. It is important that a customer adequately defines the project, and that expectations are clear. It is not unusual that a customer is seeking assistance with project definition from the independent laboratory as the independent laboratory is often considered an expert in the field.

Leggat, KTA Tator: The issue of intellectual property needs to be carefully considered while developing the scope of work. Client confidence in confidentiality is key. For example, KTA Tator has intentionally not developed the capabilities to reverse engineer formulations because we want our clients to be comfortable submitting samples to us knowing that their intellectual property is safe.

McGreer, Atlas Weathering Services Group: In our specific business, the weathering testing commonly takes a long time. Even accelerated weathering tests can take several months to complete. So timing is really one of the biggest challenges. While we can accelerate the weathering process, we must always be concerned about whether that accelerated test will actually correlate with real-world results. This is where things can get quite complicated.

Crewdson, Q-Lab Test Services: The key challenge is to make certain that we are running the best test method for the intended objectives. This means asking a lot of questions about the product such as how and where it will be used, what failure modes are likely, and what is the expected durability. There are many variables to consider when setting up an accelerated weathering or corrosion test, and it is our responsibility to make sure we are running the test that will give the most reliable results.

Other items such as confidentiality are generally not a challenge since most independent labs sign NDAs and much of the actual testing is blind. The lab only knows the specimen ID numbers, never the formulation or even the material type. Trust is key for an independent lab. The customer must be assured the lab is performing everything correctly. The good third-party labs will have ISO 17025 accreditation, with a specific limited scope that defines the test methods they are capable of running correctly.

Q. Is an independent lab typically engaged earlier in the product development process (e.g., proof of concept), or more in the later stages (e.g., optimization of formulation, product introduction)? How does your participation change based on the stage?

Marschall, Marschall Labs: Marschall Labs is involved in both early and later stages in the development process. We have assisted clients in the early stages by testing their products versus competitive control samples. The results help fine tune the client’s product to achieve greater performance.

Crewdson, Q-Lab Test Services: We are more likely to be involved in the latter stages of product development, when the new or improved product is getting close to release. This is when the results from an independent lab are used to confirm the data. The last stages in the development are to pass a specification. This is set by a company to establish minimum performance requirements. A report from an independent lab is generally required as proof of meeting the specification.

Leggat, KTA Tator: Different labs specialize in different areas. We can prepare substrate, apply coating, conduct compositional tests and evaluate performance. Different clients have different needs, depending on their own capabilities.

McGreer, Atlas Weathering Services Group: While it could be anywhere, for our testing discipline we are typically engaged later in the process. In fact, sometimes we are contacted because a product has been launched, only to soon find that there are some unexpected concerns with product durability. I believe the level or type of participation required goes back to my answer to the first question, and that is, what the research question is in the first place.

Dempsey, 1^st Source Research: We can only speak to 1st Source’s customer experiences. Over the past 11 years, it has been split evenly between the two stages. Some companies engage us much earlier in the process and require us to partner with them from proof of concept all the way through to final production. Others bring us in when they have developed the project to a point where they need external expertise to advance the project.

Obie, Wood Coatings Research Group: The answer to this question depends on the particular customer/situation. It is not unusual for an independent laboratory to be engaged in proof of concept research for new and unusual materials, or even to suggest proof of concept ideas to a customer/partner. In many cases, the customer has developed a product or material and is seeking product optimization, qualification services, market direction, or benchmarking services, i.e., later stage participation.

Swope, The ChemQuest Group: This is very customer dependent. Our participation occurs at any level of the development process, but sometimes we are frustrated because someone has wasted time and money pursuing the wrong path. We could have been more helpful if involved earlier, but that is a common issue in knowledge pursuit.

Lewis, Univar Solutions: We have done a significant amount of both proof of concept and late-stage formula optimization. Certain customers request that we evaluate and screen coating or raw material prototypes. We have also had customers send us a series of blind-labeled test panels or formulated coatings and ask us to test them to help identify a final formula. We handle both approaches essentially the same: we discuss the customer’s needs with them, turn this into actionable lab work, then send them a quotation.

Q. What are the key trends guiding innovation in the paint industry and how do they steer your research efforts?

Leggat, KTA Tator: We see a lot of coating manufacturers developing their own internal methods to validate their products. The end-users need a standard method for comparison between products. Ultimately, multiple labs need to be able to reproduce the standard method. For protective coatings, this is evident in areas such as fire protection and corrosion under insulation.

Lewis, Univar Solutions: There are a number of trends that influence what coatings and raw material suppliers have us evaluate. Regulations are changing, so customers need help with, for instance, developing a lower VOC version of a coating they already have. Right now there are significant raw material supply constraints, so customers want to reformulate their products to use ingredients that are more available. There are also coatings companies who are buying already formulated coatings and want to be able to offer a formula of their own so they can control their own destinies. Sometimes these requests can be challenging, and we might formulate several prototypes and give them options to consider.

Swope, The ChemQuest Group: As mentioned earlier, bio-derived and nano materials are prevalent, and their use is driven by environmental and performance trends. Removing “bad” actors from the equation is probably the biggest challenge for our customers. That means things like high VOC components, fugitive materials of all kinds, and anything affecting health and safety. Many current bad actors were workhorse components in the recent past.

Crewdson, Q-Lab Test Services: The key trends in the coatings industry have been to increase the durability of the product while reducing the cost and to compensate for the removal of environmentally harmful ingredients. We witnessed an increase in testing when heavy metals were banned from paints, and when water-based coatings took over from oil-based paint. These new formulations had to show the same durability. In the future, we might see an increase again as more biobased coatings are introduced, and environmental regulations look at other harmful ingredients.

Obie, Wood Coatings Research Group: I think key drivers are still related to regulatory requirements for the most part. Another important area is applicability of environmentally friendly systems. Both drivers also require a competitive cost profile.

Marschall, Marschall Labs: Product sustainability appears to be the major trend in today’s marketplace. Biobased materials are being offered to our industry on almost a daily basis.

Dempsey, 1^st Source Research: Some of the key trends in the paint industry include lowering or virtually eliminating VOCs, obtaining alternate suppliers for raw materials (due to supply chain issues), minimizing water soluble ingredients in coatings that can leach to the surface and mar the paint surface over time, and as always seeking improved product performance at a lower cost, while meeting regulatory compliance trends both locally and globally, among many others. As an independent external resource, we continually stay engaged with the latest trends and respective research to effectively support our customers. We spend a good bit of time internally on monitoring trends and reviewing the latest literature from industry and academic papers to provide a level of innovation that our customers require.

McGreer, Atlas Weathering Services Group: In weathering testing, the two words most used are “acceleration” and “correlation.” As the world moves at a faster pace, product development times are shorter, but product life expectations are longer. This conundrum is something that we are trying to deal with all the time. The interesting point is that there are currently ways in which testing times can be shortened with improved correlation. However, this may mean that the client must do testing in a significantly different way. But testing differently may mean that all previous research is no longer comparable (or no longer directly meeting the requirements of a particular material specification), and so they keep doing the same (slower) tests over and over.

Q. Do you ever perform internally driven research (versus client-driven)? If so, why and what are your key goals?

Obie, Wood Coatings Research Group: We conduct significant self-funded research. Independent research offers the opportunity to move the industry forward by helping to answer “unsolvable” industry problems or by providing research, methodologies, and/or techniques that assist the industry to better test and quantify. Providing new tools and/or better, more reproducible testing methods, allow the industry to develop new products faster, with a greater degree of success, and in a timelier manner.

Some key issues that we address in our research include test method development, coating and adhesive application, flow and leveling, drying, curing, coalescence, and structure/property relationships. In the coatings industry, results can sometimes be subjective in nature or lack reproducibility, or even lack ability to statistically characterize a result. It is important that material testing data is numerically relevant and characterized statistically as customers seek to “engineer” material properties. We believe independent research helps provide customers access to partners with enhanced creativity and who are up to date with current industry trends, and that these will be applied to their project.

Independent research also provides customers with testing and measurement methodologies to numerically access material properties of their products and materials. A specific example of this is a method called Evaporative Dynamic Oscillation Technique (EDOT). The EDOT method allows the characterization of material rheology, drying, curing, and material property development, from the time of film application through consolidation, in situ, both in terms of air dry as well as for a given oven cycle profile. Further, DMTA characterization of the coating or material film may be characterized in situ at a given timestamp. EDOT allows formulation variables as well as structure/properties relationships to be analytically characterized.

Crewdson, Q-Lab Test Services: We do conduct our own internal research to improve the methods that are being used. We are mainly driven by the published standards that our customers’ request, but there are many instances when new test cycles are needed to better simulate an end-use environment, or a specific failure mode. The goal for Q-Lab is to create test methods that give the most accurate results. For accelerated testing this means a faster and more reliable prediction of the real-world outcome.

Lewis, Univar Solutions: The vast majority of the lab work we carry out is directly for coatings companies or raw material suppliers, so we don’t spend much time with internally driven projects. But sometimes a new raw material will come our way and we will investigate novel ways of using it, then present these ideas to the supplier, which they greatly appreciate.

McGreer, Atlas Weathering Services Group: At Atlas, we are in sort of a unique situation where we actually manufacture nearly all of the instruments used in our testing facility. So, our accelerated testing laboratory can serve as an actual customer to the manufacturing side of the business. In fact, our new generation of Weather-Ometer, the Ci4400, has user-convenience features included and some of them definitely came from doing “market research” by interviewing our laboratory manager and the technicians who actually use the equipment. Atlas also participates in a number of different standards organizations and committees. Sometimes, there is test development work that is necessary, and our independent laboratory supports much of those efforts as well.

Marschall, Marschall Labs: In general, our projects are client-driven, but we do some internally driven research to keep up with new products that are offered to the coatings industry. Most of our internally driven research comes out of a desire to enhance quality and reproducibility in our testing.

Vandezande, 1^st Source Research: At 1st Source, we anticipate trends in the marketplace and try to stay ahead of the curve. We constantly scan the literature for new technologies we can apply to future projects. Our analytical department takes time to optimize our analytical tools and tweak them for faster throughput and more precise results. We also spend time updating our safety protocols and Standard Operating Procedures (SOPs). In addition, we perform internally driven research around emerging markets, new technologies or innovative trends in order to have the capabilities to meet our current or future customer needs.

Leggat, KTA Tator: As a commercial lab, our research tends to be client-driven, but we do develop new methods to address needs in the industry. Because we work with different clients and see the collective needs, we sometimes make investments to develop capabilities that an individual client would not.

Swope, The ChemQuest Group: We won’t get too specific, but one thing we often do is satisfy our own curiosity and add to our knowledge. This might be working with a new raw material just to see if it does what the inventor claims. Another area we pursue involves understanding the interplay of chemistry and equipment in solving problems. We are blessed to have both a flat line and hang line to replicate manufacturing, as well as a full array of Heraeus UV curing and Plasmatreat plasma pretreatment equipment to complement traditional ovens and application equipment.

Q. What would you like potential industry partners to know about having a successful partnership with an independent lab? Are there any misconceptions about independent laboratories that you would like to dispel?

Fox Abrams, The ChemQuest Group: There are many kinds of independent labs from national labs to universities to private testing facilities. Understanding who owns the work product upon completion is crucial to a successful project. ChemQuest Technology Institute and ChemQuest Powder Coating Research are unique in their foundation as knowledge centers staffed by industry experts with many years of experience running the same types of organizations as our clients. We are not “sample in–data out.” Our most successful client partners are eager to learn and collaborate with us. They understand the parameters around a defined project may evolve during the project because of the knowledge we provide as feedback throughout the project. These companies approach their work with us without fear of “NIH—not invented here.” In fact, they embrace the opportunity to expand their team by having access to ours.

Vandezande, 1^st Source Research: There are a few common misconceptions about utilizing an external resource. I must admit that when I was working with a few major corporations before starting with 1st Source Research, I also had some of these misconceptions. However, they simply are not real. Some key misconceptions include:

• External R&D takes longer and is more expensive than internal R&D.
• External R&D should only be used as a last resort.
• The ramp up and ramp down time for external R&D is excessive and unwieldy.

In reality, external R&D/process expertise can breathe fresh air into an organization. The right independent lab can work seamlessly with sales, marketing, and R&D providing new insights to an organization that has a difficult time breaking into new markets.

Leggat, KTA Tator: It is key for the client and the lab to understand the scope of work and what gaps will be filled. The lab needs to fill the client’s needs without trying to upsell. As an independent lab, we work with many clients who may be competitors with one another; however, it is imperative that the lab maintain the confidentiality of all client information. We can bring the knowledge and experience gained from working with multiple clients in different industries while maintaining the confidentiality of each client’s data.

Lewis, Univar Solutions: I think one of the big misconceptions is that using independent labs is expensive. We have found we can carry out testing or analysis or new product development at a fraction of the cost of hiring a new chemist. It is often very time consuming for companies to hire a new person and that person may need training to bring them up to speed with the work the company needs them to carry out. As an independent lab, we can do focused projects for companies as and when they need them, usually quicker than they can do themselves, and for a fraction of the cost.

McGreer, Atlas Weathering Services Group: First and foremost, communication is key and must be a two-way street. The independent lab needs to be proactive in communicating any concerns or asking for clarity about specific testing instructions. And our clients should always be willing to ask questions about specific testing methodologies. Speaking for our own laboratory, I think it is important to work with a lab that you can trust and has the expertise in their specific field of testing. I have many colleagues that participate in standards meeting or have years of experience doing consulting work for clients. While we can’t be expected to be experts on every specific material or product that we receive for testing, we can collaborate with our clients to combine our knowledge from the testing side with the knowledge from the material side to ensure that the testing we are doing is correct for the application, and that we can provide insight into the interpretation and analysis of the results.

Crewdson, Q-Lab Test Services: Independent labs are a great way for companies to expand their expertise and resources on an ad hoc basis if needed. The independent lab fills a need that the customer may not be able to maintain themselves. The lab can be used as needed, for example when a new paint or coating is being developed, or a new market is being explored. A good independent lab is generally easy to deal with, they are customer friendly, and they have a great deal of experience they are willing to share.

Marschall, Marschall Labs: Knowing the lab you are working with is very important. It is also important to have a trust in confidentiality. A possible misconception of testing labs is the cost involved. Individual testing labs, most times, can work much more efficiently than larger company labs because there is less bureaucracy.

Q. Do you have any other comments you think would be helpful for readers to better understand how independent laboratories are involved in the innovation process?

Marschall, Marschall Labs: Independent labs offer a unique perspective of the industry. The variety of challenges we see, along with our inherent objectivity, allows us to bring a different approach to the innovation process.

Crewdson, Q-Lab Test Services: We are asked about which tests are the most reliable, and how we can design exposure cycles to recreate a specific climate or a particular end-use environment. Laboratory accelerated tests are simulations and their success is based on how close they are to the real world. A great accelerated test is one that provides the same result as the real world but in a much shorter time. Our clients are relying on our experience to answer the question of which is the best test method for their specific requirements. Independent labs generally have a very wide knowledge base and the experience to help their customers innovate.

Fox Abrams, The ChemQuest Group: The right independent lab should bring you expertise and/or equipment you do not have in-house so you can learn faster than if you tried to hire that talent into your organization. Working with an outside partner on innovation projects allows your team to concentrate on their day-to-day activities while someone else de-risks the pursuit of innovation.

McGreer, Atlas Weathering Services Group: I always feel that an educated client is the best client for the lab. Those clients will then better understand how to interpret results. There are lots of ways to learn more about the specific testing details, whether it be online webinars, recorded video presentations, or hopefully soon, back to face-to-face meetings and symposia where ideas can be shared.

Vandezande, 1^st Source Research: To maximize your investment, choose a lab that you can trust and enjoy collaborating with, that will focus on your needs, provide solutions that are applicable to a range of technologies and products, and has all the necessary equipment, knowledge, and skills to meet your company’s project goals.

Lewis, Univar Solutions: My advice to coatings companies and raw material suppliers is to be open to using independent labs instead of trying to do everything in-house. Seek out test labs and interview them to see if they meet your needs. Ask them to give you a virtual tour of their facility so you can see their capability, rather than just viewing a brochure or a website.

About the Author

Leo J. Procopio, Ph.D., is the president and owner of Paintology Coatings Research LLC. He may be contacted at lprocopio123 (at) yahoo.com.