Test (ASTM B117)
"Film of ZRC on hot rolled steel has been evaluated against control coupons of galvanized steel in 5% salt fog. This is a supplementary report to that issued on August 29, 1990 on the same test, and details the condition of the same panels after an additional 1800 hours exposure. It has been found that the rate of zinc corrosion on the galvanized steel is far more rapid in this environment than that of zinc corrosion in the ZRC film. This is thought related to the greater availability of zinc in the case of the galvanized metal. The slight ferric corrosion, noted on the galvanized panels examined in the earlier evaluation has now progressed significantly and there is extensive steel corrosion now present. No ferric corrosion was noted on the ZRC. It is still felt that galvanized steel might have given much better protection (as good as ZRC) in a more normal exterior environment." Clive H. Hare, Inc. February 1, 1991.
Table I: 1008 Hour 5% Salt Fog Exposure Data on ZRC Cold Galvanizing Compound/Galvanized Steel Study