Q. I’m the manager of manufacturing for my company. We are basically a sheet metal fabricator. Recently we added some fiberglass parts to our products. We are trying to paint them on our existing paint line in our plant and are having problems with pinholes and blisters. Do you have any suggestions for painting fiberglass? A. W.
A. Although you didn’t say what form of fiberglass you have, I will try to give you enough information to solve the problem. Painting fiberglass is simple if you know the game.
Most fiberglass and other plastic products have mold release on their surfaces as manufactured. The surfaces must be clean (free from oily soils, mold release and dirt) before painting. If the surface is resin-rich (having a smooth, shiny surface), pinholes should not be a problem when it is clean. If the surface is not resin-rich (having a rough, striated or fuzzy surface), there could be exposed glass fibers. These fibers will act as wicks, pulling moisture into the structure. If your paint line uses aqueous cleaners, moisture can be absorbed by the fiberglass during the cleaning process. The same can happen using solvents during solvent cleaning. The moisture or solvent will come out during the paint curing process and cause pinholes and blisters in the applied coating.
To drive out moisture and solvents, heat the fiberglass to a temperature above the curing temperature of the coating before it is applied. After heating, cool and paint the parts as soon as possible to prevent the fiberglass from absorbing more moisture.
Related Content
-
Henry Ford Is Still Right When It Comes to Color
Who would have imagined that more than 100 years after his famous statement about any color as long as it’s black would still have relevance of a sort?
-
Surface Prep Solution for Rusted Rebar in Concrete
Julie Holmquist of Cortec Corporation discusses passivating corrosion on rebar and other reinforcing metals.
-
Zinc Phosphate: Questions and Answers
Our experts share specific questions about zinc phosphate and pretreatment
