Comparison of Tracking Test Methods

A selection of epoxy specimens has been subjected to a number of different tests for track resistance. The degree of agreement between testing agencies using the same method, and between the different test methods is described. Generally speaking, those methods, which impose alternate wet-dry cycles, or otherwise simulate the "dry-banding" effects that occur in service, appear to classify meterials in the "correct" order, that is, in best agreement with each other, and with actual outdoor performance. The superior track resistance of cycloaliphatic systems, and the further improvement consequent upon the use of hydrated alumina filler are confirmed. Details of the Tracking Endurance Wheel Test method are given in the Appendix.