Dust Control and Conversion Varnish

Tips on protecting against dust and overspray when spraying CV. March 9, 2010

Question
I recently used Sherwin Williams Kemvar conversion varnish for the first time. I was drawn to the finish because the project was a solid 3x5 maple top for a kitchen. The shop is small Ė 3,000 square feet with an open face spray booth. There is no machining or sanding during this process, but thatís not to kid myself and think the air was pure. We have two air cleaners that hang down from ceiling trying to get some of the dust. The product is a very good product and the end results were ok. We had some defects in the finish. I concluded that our environment isn't conducive for this type of product to reach its maximum potential. What experiences have other people had with this product? Small shops in particular. Any insight would be appreciated.

Forum Responses
(Finishing Forum)
From contributor A:
The air cleaners are probably part of the problem. You need to get the shop as dust free as possible. Start by removing the obvious debris with a broom. Spray fan should be as close to the floor as possible. Start at the back of the shop and use an air hose to spray the dust off of everything, including your hanging filters which are in the air stream. Blow it toward the fan, pushing it out. Leave the fan on for 30 minutes after you stop air hosing to let the remaining dust settle. You also need to consider where your makeup air is coming from. The window or door may be contributing to your problems. I doubt the finish is the issue. It sounds like a dusty environment.



From contributor R:
Contributor A points out some great housekeeping ideas to keep your spray area as dust free as possible. I might add that you could also spray some water onto the floor using one of those pump sprayers that are usually used to apply a pesticide or a deck stain. These are pretty good units to have in your arsenal of "tools" and they are reasonably priced. Kemvar is just one of the many coatings that Sherwin Williams makes and I find it to be a good choice over a regular nitrocellulose lacquer.

Most seasoned finishers would likely cringe if they saw some of the shop conditions in which Iíve sprayed coatings, but keeping the spray area as clean as possible will help you achieve a fine finish. If dust in the finish is your main objection, police your area with a finer toothed comb. If cracking and crazing (the Kemvar curse) become an issue, they can easily be resolved with some additional heat in your spray area. Donít give up on the Kemvar, I think itís a good product.



From contributor K:
As small one man shop I find it is best to spray first thing in the morning before the dust has been disturbed. I only have 1800 SF so my production and finishing share a lot of space.



From contributor J:
Please consider the overspray. It does not melt back into CV. Make sure your exhaust is working properly and don't spray towards a part that is all ready coated.