Paints & Coatings Resource Center

Ask the Expert Question-and-Answer Archive

by Ron Joseph

October, 2005

Use of Silicone Sealer in Spray Booth Construction - Fish Eyes - Cratering

Q. I recently attended the paint training class offered by Akzo Nobel and heard some horror stories about silicone contamination in paint facilities. Of particular interest was a problem caused by contaminated thread (which passed over a spindle lubricated at some point with silicone) that was woven into filter bags. Very difficult to track down. My concern was introduction of silicone during construction of a paint facility. Could a silicone containing material such as pipe dope or RTV silicone sealing in ductwork cause problems? I asked an engineer form Boeing if they had ever encountered such a problem and he told me Boeing put a prohibition on silicone into contracts when constructing paint facilities. As you are probably aware, Warner Robins is building a new paint facility, so I asked the chief engineer for the project if there was any language to that effect in our contract. The short answer is no, and he was unaware of the problems silicone can cause. When I asked the folks at the AFCPCO if they had ever encountered any silicone problems from construction of paint facilities the answer was no, of all the sites surveyed for the Facilities Hand Book they put together, there was no mention of any silicone related problems. Hence the question, have you ever encountered a silicone problem as a result of construction practices? Is concern during construction warranted, or is contamination always after the fact, introduced into a facility somehow? Or is silicone contamination rare in general? Thanks.

A. I'm sorry it has taken so long to get back to you, but I mislaid your email.

I have not heard of paint booth problems when silicone is used as a sealer, but I also confirm that silicone is a poison in any paint facility. Unfortunately, when paint cratering (fish-eyes) occurs it can take week or months to identify the source, and often the source is never found. If I were to be retained to solve a cratering (fish-eye) problem I would look for all sorts of sources of contamination before looking at the sealant in the sheet metal of the booth or ducting.

Therefore, if at all possible, I suggest that you keep this elusive chemical out of the system. nobody will thank you now, but they surely use lots of four-letter expletives if a problem occurs and they dfound out who initiated it.


Ron Joseph

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