Q. I saw the listings on your web site for different types of painting. I was wondering if you could possibly send me some information on painting zinc. I work for a company that builds stained glass windows, lamp shades die castings and various other decorative objects. We are working on a project that requires the zinc to be colored. I suggested that perhaps we could paint the zinc. I know how to paint, but I am not sure about how to paint the zinc. I understand that it is tricky. Any information you could provide will be very helpful. Thank you so much. A. C.
A. Painting zinc is not really tricky. When painting zinc, you follow the same rules as painting galvanized surfaces. I am sure any paint supplier can provide a number of applicable products. I would avoid applying paints containing oleoresinous and oil modified vehicles directly to zinc surfaces because the zinc may cause them to be soponify and lose adhesion. However, the aforementioned products may be used if the zinc is passivated by treating the surface with a compatible pretreatment. As with any substrate, zinc must be thoroughly cleaned before pretreatment using solvents or aqueous cleaners to remove oily soils. Typical pretreatments for zinc include phosphates and chromates. A phosphoric acid activated vinyl wash primer is also an excellent pretreatment for zinc surfaces.
Organic zinc rich primers have been used successfully on zinc surfaces. Depending on the exposure conditions your products will see in service, a number of others coating types can be used. Other candidate coatings types to consider are single package epoxies, two component epoxies, two component polyurethanes and vinyls. Again, clean the surface, pretreat if possible and apply the right paint. That’s not too tricky, is it?
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