Ask the Expert Question-and-Answer Archive

by Ron Joseph

March, 2004

Inorganic Zinc Silicate

Q. IOZ inorganic zinc silicate has been applied in a tank that holds service/sea water. I would like to know where I can find relevant documents on using a zinc silicate primer for emersion purposes and the implications of topcoating or leaving the primer for service.

A. I have never seen an inorganic zinc silicate primer that can be used for immersion purposes. There is so much zinc in the coating and so little resin that I simply can't imagine that one can successfully dip parts into such a coating. On the other hand, recently I went to a company which uses an organic zinc rich coating into which they dip small component parts. Even then, the coating applies very thick and does not have a good appearance, but it seems to serve the company's purposes. Sherwin-Williams makes their zinc-rich dip primer.

Incidentally, the company topcoats the zinc with a high solids, single-component polyurethane, but the components are used on vehicles and not for immersion in sea water.

One source that you might refer to is the manual from the Steel Structures Painting Council (SSPC), located in Pittsburgh, PA.