Troubleshooting Pinholes in a Lacquer Finish
A pinhole problem is traced to a dessicant cartridge that needs replacing. December 23, 2014
Question (WOODWEB Member) :
I'm having trouble trying to get rid of these pin holes in the second and third coats of Kem Aqua Plus. I'm spraying with a conventional Devilbiss and a thorough cleaning hasn't changed anything. They've always been there but now that I have a higher-end pigmented lacquer job I have to get rid of them because they are so much more evident. Has anyone else run into this problem?
Click here for higher quality, full size image
Forum Responses
(Finishing Forum)
From contributor W:
Fisheye. Is your air clean and dry? We had the same problem with a different waterbased product and traced it back to a desiccant cartridge that needed replacing.
From contributor G:
Doesn't look like fisheye to me. Looks like bubbles that popped just as it was skinning over.
From the original questioner:
One thing I have noticed is that I don't tend to see them until a few minutes after spraying if that helps at all.
From contributor G:
Fisheye is nearly immediate.
From the original questioner:
I am sincere when I say you just saved me a lot of time looking at other possible causes. Wyatt you nailed it. I thought my air was dry enough but the desiccant filter was obviously too wet. New desiccant and an hour running alcohol through the lines and blowing everything out has fixed the problem. I didn't realize how bad it had become until shooting the pigmented lacquer for this job. I need to get some sort of indicator that will let me know when my desiccant is ready for a change.
Click here for higher quality, full size image
From Contributor C:
When I worked in a clean room, we used color-indicating silica of some sort though I can't recall the exact product name. This assumes that the canister containing your desiccant is clear or has an observation window of some sort, naturally.
From the original questioner:
Unfortunately my dryer has not windows in it, it is made of metal. But I am in touch with a local supply company that might be able to order something that will bolt on to the output of this dryer with a color indicating desiccant window in it.
