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Issue link: http://coatingspromag.epubxp.com/i/564332
82 SEPTEMBER 2015 COATINGSPROMAG.COM scratches in the coating were prevalent and one area where the coating was thought to be in a "near pristine" condi- tion (sampled in an area of little use). Note that this doesn't mean we took three core samples, but rather several samples within these three areas. Once the cores were taken, they were then shipped to the lab where the appropri- ate testing would take place. I called the coatings applicator and asked for coatings test tablets from the original installation. Te test tablets, sometimes referred to as coupons, are usually made and retained for refer- ence as to the specifc makeup of the foor install, and they would make the comparison testing at the lab so much less complicated. Te preparation of test tablets, typically one or two small samples of applied coating for each batch mixed on site, can be critical when it comes to the evaluation of problems later in a coatings service life. Te tablets, if properly stored, provide an undisturbed and pristine representation of the coating as it was originally mixed and cured. Tey would show the foor's condition before any contamination by maintenance chemicals, spills, or everyday use. Unfortunately, test tablets were not made during the course of the original installation, which is a fairly common but neglectful and sometimes expensive practice. Te applicator, though, was willing to supply a small batch of the coating; however, it was in its liquid state and therefore unpre- pared. I had the lab mix and then apply the coating to a series of test tablets, per the manufacturer's printed instructions. From there, the testing protocol was simple enough. Te lab completed a microscopy examination of the coating, which is a visual examination by microscope usually involving a set of observations under diferent powers of magnifcation. Tis was done to determine whether or not the coating thickness and overall coating condi- tion matched with the manufacturer's instructions. Te lab also completed a Taber Abrasion Test to judge abrasion resistance per ASTM D4060-10: Standard Test Method for Abrasion Resistance of Organic Coatings by the Taber Abraser. Taber tests involve mounting a fat specimen, approxi- mately 100 mm (3.9 inch) square or round, to a turntable platform that rotates on a vertical axis at a fxed speed. Two abrasive wheels, which are applied at a specifc pressure, are lowered onto the specimen surface. Te evaluation criteria may include loss in breaking strength, yarn breakage, loss in coating, change in gloss, color loss, or other changes in appearance. In these cases, the abraded sample is usually compared to a known standard of the material tested. W hen visually inspecting changes in specimen appear- ance, evaluations should be made using an agreed-upon rating system, such as a visual grading scale (e.g., fve-step) or pass/fail criteria. Analyzing the Results About two months later, the news came: Te coating was too soft, and, as applied, it failed the Taber Abrasion Test. Te underlying cause was believed to be improper mixing of the product Additionally, the chair casters were evaluated. Those were plastic and had embedded particulate also. The question posed to the manufacturer's rep was "After half a year of service in the middle school setting, should the floor look like this?" When he suggested to get it tested, we agreed. Never Again