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I've been having troubles with fisheye on and off for most of this year. Hoping to get some outside perspective on what the cause might be, and whether some assumptions I've made are logical. To give some background info, this is my finishing room setup;
5hp piston compressor w/ refrigerated air dryer + desiccant dryer & filters @ booth. My air piping is 3/4" galvanized steel. We spray only Axalta solvent based conversion varnish. The finishing area is a separate building from the main wood shop so I'm confident there isn't an airborne contamination issue (silicone etc.)
We have two kremlin 10:1 systems (one for pigmented, one for clear) as well as a few gravity feed Devilbiss guns. The fisheyes are only happening when we use the pigmented kremlin set up. This leads me to believe the issue can't be related to water or oil coming from the compressor or piping system.
I thought maybe the cartridge that keeps the piston lubricant from seeping down into the chamber where the paint is could be worn, therefore allowing the lubricant to get into the paint and cause the fisheyes. We disassembled the fluid section of the pump, thoroughly cleaned everything including removing all of the lubricant from the reservoir and reassembled. We refilled the reservoir with lacquer thinner temporarily to try running the system. For about a week or so the issue was 95% solved, and then slowly started to get worse and worse again. We've been using thinner as the lubricant the whole time so I'm stumped as to what the issue could be. Is there anything in the upper air section of the pump that could be causing this issue?
At this point I'd happily spend the money on a new system, but it's kind of a gamble as I really don't have an answer on where the problem stems from. Thoughts?
Are you sure it's fisheye and not something else. I've dealt with fisheye and it can be pretty devastating and notoriously hard to get rid of because you can't see the contamination.
Is it a fisheye here and there or is the substrate peckered with them?
I guess it's possible that it could be something other than fisheye.
They were showing up on every piece sprayed last week. When recoated using the gravity feed gun there were none, which makes me suspect its coming from the kremlin.
Well that a good sign that you don't have room contamination.
I use plain old mineral oil in the lubrication cup on my Kremlin 10:14.
Not much that can become contaminated in the pump. The hoses are one item that can hold onto contamination.
Run several different thinners through the pump. End with Denatured alcohol. Use a different cup for each one, don't recycle the thinner through the pump, just in one end and out the other and dispose.
If that doesn't work change out the fluid hose. If that doesn't work change out the air hose.
Simple test if it's your spray system or air. Use a large piece of glass, say 2x2. clean with acetone or alcohol using paper towels and do not blow dry. first test, turn off the atomizing air spraying with no air just paint (yes there will be streamers) and see if any fisheyes. If not clean off glass again and this time make several passes over glass like you are spraying with just the air and no material. then right away spray is as usual and see if any problems.
I have had what I thought was fish eye, but was actually small pecks of dried finish falling from the gun or hoses. When the dried finish fell, the wet finish would repel from the specks and look like fish eye.
I have found that keeping the gun/hoses a little cleaner has eliminated the problem. I also wear a Tyvek suit as well.
I am using a CAT AAA.
Buy a brand new hose.
If you own a conventional or gravity gun wash it with acetone.
If you donít own one buy a new one. Itís always nice to have a decent inexpensive gravity gun on your shelf. I like the Astro Pneumatic/Starr)
Shoot something OTHER than your regular snot. You have now removed several important variables.
Then work by elimination and adding variables one at a time. You can clean the gun with acetone to keep it pristine.
Good luck contamination fish eyes are the most annoying thing in finishing.