QuestionI am finishing a project (all urethane) with clear coat. Many small tube shaped parts. I have to keep the pattern small. When I color sand and polish (3M Trizact and 3M Perfect it), tiny little white spots appear. After much trouble shooting I've learned:
1) Halogen lighting is not good for painting - it dries the clear before it hits the part - I am now using florescent
2) Clear coating requires larger tip - 0.8mm too small - I am now using 1.2mm
3) Less air with clear is better
I am still getting small white spots in the clear. My impression is that I am still getting dried paint before it hits the piece. Any idea what is causing this?
Help me Gary - you're my only hope!
Thanks!
AnswerHi Greg,
It sounds to me that you still have dried clear hitting the panel. What I would recommend is that you do the following:
1) Use a very fine micron strainer just so that you can eliminate trash as a potential problem.
2) Use super slow drying reducers. Something designed for 100+ degrees. This should allow the clear to get to the panel without dry spraying. I always use a recommend that everyone use at least one step slower reducer than the temperature would normally call for. (i.e. use 80 degree temp. reducer in 70 degree weather.)
3) Make sure that you are not too far away when spraying. 8-10 inches (from nozzle to surface) for a gravity feed gun is best. To far away allows for too much of the solvents in the clear to evaporate and will actually cause dry spray.
4) Make sure that you are using the correct pressure designed for your spray-gun. Check the model number and then check the mfgrs. website or the paper work that came with your gun. To high pressure causes the solvents to evaporate before the material gets to the panel.
5) Make certain that your air line is clean. I actually had this happen to me. I had an aluminum body air filtration unit that had corroded on the inside(I wasn't servicing it properly). When aluminum corrodes it leaves behind a white powdery substance. I was getting this in my paint jobs and it about drove me crazy trying to figure out what it was. Finally, after a couple of re-paints I committed to track down the problem and found out that my airline was contaminated with this junk. I replaced the filter, regulator, and air hose and the problem went away. I don't really think this is your problem but it doesn't hurt to investigate it to eliminate future issues.
I hope this helps, and if you have any other questions please feel free to ask.
