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Wet Spots in Finish
Question
For instance, I was working on an old trunk recently that I finished a while back. I set it aside to order some leather for the handles and decided to final coat it and when I finished I noticed that I had some random spots that just would not dry. I tried hitting them with a light breeze from a hair dryer to no avail and I am just wondering what causes this and how it can be avoided. Does anyone have any suggestions? Forum Responses
From contributor M: Are these spots on pieces that you stripped? Or are they pieces that you cleaned and de-waxed and then recoated. From the original questioner: These are usually on pieces that I have stripped using Benco B-1 stripper. It doesn't happen consistently making it harder to trace.. It's like the whole entire bottoms of a set of drawers I spray will lay wet for hours. I use a Kremlin MVX gun and a 10-14 pump. I am sort of at a loss for an explanation. The funny thing is that none of the other parts of the piece do this. They all dry to the touch within 15-30 minutes but these it seems will never dry and some places literally never dry. They always look wet until I mist them with naptha from a spray bottle. I will have to admit I am clueless on this one. Today I promised that trunk to a customer. I sprayed it, set it in my curing area, she came in like five hours later and there were wet spots. I had to send her home and without the piece.
From contributor S: Wax in the stripped areas, strippers not dry where the wet spots are present possibly, all points back to contamination somewhere. Final wipe your stripped pieces with Acetone and see if that helps. From contributor M: You need to do a better job of removing the residue of the remover. I suggest you use Acetone or Lacquer Thinners as your final clean up with steel wool or the nylon rubbing pads. What is happening is that you’re not removing all the stripping residue, and then when you spray you are reactivating that residue. Sometimes a damp cool cloth wiped over the wet spots may take away (not remove) the wet spots, naptha, or mineral spirits also may work with out affecting your new coating. The key to eliminating them is to clean the pieces better with a solvent.
From contributor R: To the original questioner: Are you using a catalyzed lacquered/varnish? If so, my experience says it's directly related to the stripper. My experience also suggests that the stronger solvents such as lacquer thinner and acetone don't totally solve the problem. After my last experience I talked with a tech at the company manufacturing the stripper. He recommended mineral spirits since the type of wax was incompatible with lacquer thinners and acetone. So I haven't had opportunity to really test that, but try thoroughly washing with mineral spirits next time and see if that helps. From contributor T: The late Jerry Metz routinely advised against using conventional finishes on drawer boxes, and recommended a drawer-finish, which was a wax-based spray. This wax on raw wood doesn't strip or rinse easily, so that could be your drawer bottom problem. Contamination (residue of stripper/old finish) as mentioned is likely the cause of the random spots. A misting and/or wiping with clean cold water is very effective at forcing these areas to dry, although sometimes with a higher gloss than the rest of the surface. From contributor R: To contributor T: Do you know why Jerry recommended that? From contributor M: It's usually residue of wax that inhibits the lacquer drying. Try passing a damp/wet rag (using water) over the area. Somehow, when the water dries it helps dry the area, and the wet spot usually disappear. From contributor T: To contributor R: I believe he was addressing the concerns of blocking, sticking, and odors.
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