Q. I operate a one-man powder coating shop and I have tough time stripping OEM coatings from car wheels. I have tried a methylene chloride based stripper as well as a benzyl alcohol stripper and found them both to work well for a while until they get loaded with sludge. I am wondering about using pure methylene chloride as a paint remover with a water blanket on top to control the fumes and distilling the methylene chloride laden sludge in a solvent distiller to recover it for reuse. Is there any reason this is not commonly done? I can find no information anywhere on the recycling of used MC stripper though it seems to be a very viable candidate for solvent recycling with such a low boiling point. I greatly appreciate any assistance you can offer.—A.M.S.
A. Methylene chloride can be an effective paint stripper either alone or in conjunction with other solvents. However, you need to be aware of the toxicity and environmental issues related with it. While a water blanket would reduce evaporation and emissions, it would still be an environmental problem for disposal. Recycling of the solvent may be viable, depending on the paint type used. You would need to use safe and “tight” equipment when doing this, which may counter any cost savings. Your primary savings would likely be greater for the disposal costs incurred. Some sort of simple filtration system may be more cost effective at removing some of the sludge without the expense and uncertainty of the distillation system.
The German Association of the Automotive Industry’s VDA Volume 19 is the first comprehensive standardization document for characterizing the cleanliness of products within the automotive industry’s quality chain.
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