Yet Another Fisheye Mystery

Finishers add more names to the long list of usual suspects in a fisheye case. April 19, 2011

I was wondering if any of you would share all of the different causes you've experienced for fisheyes in the hope that I might find my cause. It crops up every couple of weeks and I can't figure out where it's coming from.

Forum Responses
(Finishing Forum)
From contributor W:
I suspect your crater problem is caused from the environment air. Check the place around your shop, there may be some peoples of factory that do some activities that create some silicon or other contaminant material. The materials is blown by the air and come in your shop. What you can try to do is make your finishing shop is close enough from the outside air.

From contributor M:
I heard of a shop that nearly went bankrupt because they couldn't get fish eyes out of their finish. After six months of new guns, lines, cleaning, and changing products, they traced the problem to the purchasing department who had started ordering powdered gloves because they were cheaper. The powder contained silicone, causing everything they handled to fisheye.

From contributor A:
There are dozens of causes. The latest one I've figured out is the harbor freight blowers that we give to our sanders. Heavy coats of any material will cause fisheye, especially. 2K urethane. If you think you have oil/water in the airlines, keep a supply of the disposable filters that screw to the spray gun

From contributor S:
If it just crops up periodically it is most likely coming in airborne from somewhere else. Silicone based products are the most obvious but not only concern. Airborne particles of many kinds can cause it too. Determine if you have neighbors doing a suspected operation.

Metal working (coolants and particles) or polishing (compounds and particles) nearby can ruin a finishing operation. Sometimes I think there must be close to a gazillion products that contain silicone based formula's. If it ends in "icone", ie dimethicone, it's a likely suspect and it can migrate like crazy. If you get inundated with it, it can be a nightmare to clean out but it can be done. First you have to stop it from entering your building.

From the original questioner:
I don't think it's coming from the outside air. It could be water in the lines, but then I would think it would be more consistent. I don't have an air dryer, but I can go for weeks without a problem and then just like 5 minutes ago, a 2' x 8' panel was littered with about 100 fisheyes. This is new work, not refinishing. This particular project is pigmented conversion varnish.

I have a new theory I'd like to run by you guys after this morning. Is it likely that older material that has been freshly catalyzed could be the culprit? This particular end panel was sprayed with 1 coat of SW Kemvar Primer and no fisheyes. I followed that up with a coat of leftover white from a previous job that I'm using as a build coat - no fisheyes. Finally, I put down the final color coat of white, freshly catalyzed from a bucket that's been around for a few years but never opened, and crazy fisheyes.

From contributor G:
Fisheyes rarely show up in a first coat. I would say either your second to last or last coat has some sort of contamination in the finish. Do a test only using a primer and the final coat to see if it fisheyes. If not, then do a primer coat the second to last coat and then the final coat and see if it fisheyes. This will tell you if there is contamination in one of those buckets.

From contributor A:
If you’re going to look at your material, go and get yourself some glass for windows. Get them cut in sizes like 10x10. Clean them well with acetone and spray out your products. You then can see if it is the product, especially on the first coat. When I was with Akzo, we once had fisheyes caused by mixing three different batches of catalyst together.

From the original questioner:
I'm in the midst of an experiment to see if it might be my thinner. SW recommends Butyl Acetate, which I used for years without fisheye problems. In the last few years, I've switched to just plain lacquer thinner, and even more recently to a less expensive lacquer thinner.

From contributor F:
I can't believe no one has mentioned WD-40. I had a horrible time tracking down the cause of fish eyes on a conference table a few years ago and finally traced it to the cabinetmaker that built the table who had just re built his belt sander and lubed it up with WD-40 before sanding the table top. I won't let the stuff in my shop.