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| TEST METHODS |
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methods are designed for two purposes: 1. Performance reliability, (i.e.,to determine the suitability of a coating for a given use.) 2. Quality control, (i.e., to maintain uniform quality in coating application and raw materials applied.) Some laboratory tests for reliability can be related directly to performance under service conditions, thus making coating evaluation simple. However, in other cases the evaluation of a coating in the laboratory is inadequate either because of time, or because there are no suitable methods for measuring the desired properties, or because the coating is designed for long-term service and the laboratory tests cannot be correlated. Generally, it is not possible to devise short-term tests that will give positive correlation with service because the tests must be accelerated by increasing the severity of exposure. Laboratory tests are set up to screen coatings, and the selected coatings must then be evaluated under actual service conditions. If a given material performs better in carefully selected laboratory tests, the formulator is generally confident that it will also perform better in actual service and will therefore approach field trials with considerable optimism. Some examples of tests that are commonly performed on products that have been powdercoated are listed below: |
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