Ask the Expert Question-and-Answer Archive

by Ron Joseph

July, 2005

Zinc Phosphate Corrosion Protection

Q. Is zinc phosphate a rust inhibitor? I have a steel part that is leak tested in water for less than 3 minutes, but I can't dry it off after the test and the water sits on the surface until natural evaporation takes place - maybe a day or so. In service, the coated (zinc phosphated) steel will not see water.

A. A properly applied zinc phosphate pretreatment (TT-C-490 Type I) should easily withstand contact with water for 3 days; however, if you can speed up the evaporation by blowing air (or better still warm air) over the part, you will fiurther minimize the opportunity for flash rusting.

Best wishes,

Ron Joseph