Corroded Roof Problem

Q. I own an electroplating shop in Massachusetts that has a metal deck ceiling with trusses that are rusting due to the plating. Can anything be applied to the ceiling to prevent further corrosion?—P.K. 

A. There are several things you will need to consider as you endeavor this project. First, do you want a long or short-term solution? Next, is the metal to be painted galvanized or structured steel? Lastly, how thorough of a metal cleaning job can you perform?

With most paint processes, it is crucial to remove all the existing paint flake and rust completely down to clean metal. Sandblasting is particularly effective in achieving this. The long-term success and warranty of many coating processes are contingent on this important step.

If you want a short-term solution that would minimize this cleaning process, take a look at a two-part epoxy system that can be applied over a sound metal structure with rust. My recommendation for a more long-term solution, however, would be a wet paint that incorporates polyvinylidene fluoride (PVDF) or a comparable resin system. PVDF products have very high chemical resistance ratings and are unaffected by most chemicals. They also offer superb resistance to acid, solvent, bases and heat.