The Importance of Sample Taking in Failure Analysis of Paints and Coatings
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Many expensive-sounding analytical tools help an experienced investigator determine the cause of a coating failure. For example, infrared spectroscopy can determine such things as coating type, contamination, and mix ratio; gas chromatography can detect residual solvents in paint chips and blister liquid; differential scanning calorimetry can measure relative degree of cure; and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) can detect and characterize inclusions, debris, and failure planes. However, the best-equipped laboratory is still limited by the type and quality of the samples that it has to work with. This article will discuss the type of samples needed for failure analysis, and give suggestions on how to obtain them.
Because of the extreme variety of coating types, substrates, and environments, there is no “cookbook” method for conducting a failure analysis. Consequently, there is no cookbook procedure for sample taking. The...