White Film after Spraying

A contaminated air line and filter turns out to be the culprit. March 12, 2015

Question (WOODWEB Member) :
Iím getting a white powdery film on furniture after I spray finish the piece. I use Gemini flat pre-cat finish. I have waxed and buffed and still get the same results. Does anyone have any thoughts.

Forum Responses
(Finishing Forum)
From Contributor B:
What did you stain and seal with?

From the original questioner:
I stained with Old Masters wiping stain and finished with Gemini lacquer. I followed that up with a couple of coats of Antiquax wax. I have been doing this for some time and just started having troubles with this white dust. I will get the dust sometimes even if I don't wax. Iím thinking itís got to be a temp or humidity problem when I spray. I just have a separate room where I finish but itís not climate controlled. Itís been pretty humid lately but I had the same problem off and on this winter also. Iím not sure whatís going on.

From contributor K:
There was a recent post about a similar issue and it turned out to be the compressor lines. It was said that there was a white rust that develops in the piping (from what I recall).

From contributor H:
I would take a real hard look at the compressed air filters located before the gun. If in the budget get a refrigerated air dryer, a coalescing filter before the dryer and a good quality airline filter after the dryer. Be sure you run your airlines so that you have a drain leg and it comes off with the air line with a t beforehand. A good set of airline filters might cost you less than $300, don't skimp on them. Itís very inexpensive insurance.

From contributor C:
It sounds like moisture in the finish.

From the original questioner:
Ok so my compressor had water in it and my inline filter was pretty soaked with a white mud. This has to be it. I have to confess I have not checked for moisture in quite some time so it's all me. What can I do to the pieces I have with the dust? I don't want to strip finish and start over. What can I do?

From contributor K:
Take a small piece and mist some retarder thinner over the surface. A light coat is all you need. Give that a shot Ė youíll be surprised what retarder thinner can do to lacquer that has moisture issues.

From Contributor R:
I agree with trying what Contributor K suggested but first off get rid of the wax you said you applied. You can do this by cleaning it off with some elbow grease and a rag dipped in paint thinner or Naptha. Prior to misting on some retarder make sure the piece is bone dry of P/T or Naptha.