FR performance and durability depend on the chemical composition of the fiber, and frequency of exposure to heat and flame. Most reputable vendors offer products that are guaranteed for the life of the garment. As a rule fabrics that are processed to be fire resistant during production are more enduring than natural fibers that are merely topically treated with chemicals to make them fire resistant. Longer wear life can be attained by following the proper care and cleaning procedures. There is no way to test the relative safety or condition of an FR garment that is being used without destroying the garment. The result of testing one garment used in the program does not indicate overall condition of all garments in the program. It is prudent to observe the guarantee provided by the manufacturer to determine replacement period of the FR clothing. This is just one more reason to rely on a good brand name product instead of un-tested low cost substitutes