Q: I work for an overhead garage door company, and we powder coat the extruded aluminum rails for some of our doors. We have had issues in the past when trying to change the window caulking to something with silicone in it.
Our management team is now wanting to change caulking again, and I’m looking for your professional opinion and some documentation to confirm that what we experienced before is indeed true.
A: You are wise to be cautious before making the switch to a silicone-based caulk. You mention that the operation had issues in the past with the use of silicone window caulk, but you weren’t specific. I can make an assumption and conjecture that the powder coating exhibited film defects such as craters and possibly “fisheyes.” These occur when a contaminant has a surface energy significantly lower than the resinous portion of a powder coating.
Silicones and other oils, lubricants, and greases all fall under that category. Indeed, other sources can include body lotions, cosmetics, textile finishes, and even some fragrances. The contaminant can emanate as a mist, a particulate, or even on a molecular level as a fume.
One thing is for sure – most (if not all) silicone-based materials will cause cratering in a powder coating finish. Cleaning to avoid contamination usually falls short of eliminating the incidence of defects. And as the article points out, most cleaning materials and methods do not successfully remove 100% of a silicone contaminant.
Hence – run fast, as fast as you can from introducing silicone caulk into your plant. You’ll be glad that you did.