The general idea is to subject the specimen to salt fog for extended periods in a controlled environment. In the case of Coil Shield, treated coils were exposed to salt fog, then UV light accompanied by high temperatures, and an industrial atmosphere containing sulfur dioxide. Coil Shield was exposed for 1,500 hours with no corrosive damage to coil fins. The test was then continued until fins on untreated coils were falling off copper tubing. Coil Shield specimens were structurally intact at the end of this 4,000 hour test period.