Paints & Coatings - Lab Testing and Failure Analysis

Tremendous financial losses are incurred every year as a result of premature failure of paints and coatings. Costs of such failures far outweigh the initial costs of painting because of the complexity of repairs and the liability associated with downtime to correct the problems. MATCO's Coatings Division resolves coating failure problems by application of the techniques listed in the table above. MATCO performs a wide array of standard ASTM and NACE test procedures. However, it's not only our equipment that sets us apart from other laboratories, it's our expertise. Our SSPC and NACE certified coating/corrosion professionals will look at the paint failure from both the paint formulation and corrosion/substrate point of views and know which technique will provide the most useful information, given the nature of the failure.

For example, gas chromatography is excellent at detecting solvents, but would be of little use in determining why an alkyd resin failed. Another example is that only EIS and exposure tests can distinguish between storage related problems and paint application/formulation problems in white rust formation on painted galvanized steels. Traditional approaches cannot make the distinction. These insights could save unnecessary effort and expense, simply by selecting the right test.

The majority of paint and coating-related failures can be attributed to six primary causes. These causes are as follows.

1. Improper surface preparation – the substrate surface is not adequately prepared for the coating that is to be applied. This may include cleaning, chemical pretreatment or surface roughening.
2. Improper coating selection – either the paint or coating selected is not suitable for the intended service environment, or it is not compatible with the substrate surface.
3. Improper application – this can be a problem with either shop-applied or field applied coatings, and occurs when the required specifications or parameters for the application are not met.
4. Improper drying, curing and over coating times – again, this problem relates to a lack of conformance to the required specifications or parameters.
5. Lack of protection against water and aqueous systems – this is a particularly serious problem with aqueous systems containing corrosive compounds such as chlorides.
6. Mechanical damage – which results from improper handling of the painted or coated substrate, resulting in a breach in the paint or coating.

There are innumerable possible failure modes which can result from these primary causes, that are categorized into the three following general areas:

1. Formulation-related failures.
2. Substrate-related failures.
3. Physical defect-related failures.

These three general categories of failure modes will be described briefly.

Formulation-Related Failures

There are many types of paint and coating failures for which the coatings or corrosion engineer has little or no control over. These types of failures are related to the formulation of the coating itself. If the coating system that is selected by the engineer is formulated inadequately, the coating will most likely fail regardless of all efforts made in an optimal application. These formulation-related failures occur as a result of the ingredients used and their formulation in the paint or coating. These ingredients include the resins used, the pigments used, as well as the solvent formulation. Several specific types of formulation-related failures are presented in Table 1, as well as appearances, causes, and problem prevention. They include chalking; erosion; checking; alligatoring; cracking; mud crack; wrinkling; biological failure; and discoloration for organic coatings; and checking; mud cracking; and pinpoint rusting for inorganic (zinc) coatings.

 Table 1. Formulation Related Failures

(Source: Steel Structures Painting Council, Causes and Prevention of Paint Failure)  

(Source: Steel Structures Painting Council, Causes and Prevention of Paint Failure)   

In our paint failure investigations, you will be kept informed of results as they become available. Each failure analysis investigation will include a formal report containing the description of the defect, review of the application and exposure conditions, chemical analysis of the paint to check against specifications, on-site and analytical test results, factors influencing the paint failure, identification of failure mechanism and root cause, related problems, and corrective actions if requested.

Paint and Coating Analysis Team

Our diverse Paint and Coating Analysis team is comprised of independent certified coating experts and personnel from a variety of technical disciplines including: mechanical engineering, cathodic protection, chemistry, metallurgy, and materials science.  We also have a vast array of laboratory and field testing equipment. All of our laboratory testing equipment is calibrated on a routine basis in accordance with both national and international standards, and is ready to be put to use at a moment's notice.

Please review our newest internal publication, "Failure Analysis of Coatings" by Dr. George T. Bayer and Dr. Mehrooz Zamanzadeh.

Our Paint & Coatings Analytical team includes chemists, coating specialists and NACE Certified Materials Selection/ Design / Corrosion/Coating Specialists (*) includes:

Dr. M. Zee(*)                                    Dr. George Bayer

Ms. Debra Riley (*)                           Dr. Huiping Xu

Mr. Sam Scheinman                         Dr. Donald Gibbon

Mr. Walter Gretz, PE                       Mr. Antonio DiNunno

Paint and Protective Coating Laboratory Testing Available: