Clear coating question

Hi folks, Corky Scott with another spray painting question. As I mentioned previously, I'm having a problem with water in my air line. It's causing drops of water to get sprayed on the object I'm painting, which then get covered with paint. So I get bubbles of water encased in paint. I have to sand them off and down through the base coat to eliminate them, and then repaint. I've done this three times, and have to do it again now.

One other aspect of being delayed from finishing is that the window of opportunity to apply the top (clear) coat has passed. I understand from the literature that I have roughly 24 hours to apply the topcoat, with no need to further prep the base coat, and the top coat will chemically bond to the base coat.

But since I had to stop with this last piece, because I did not want to be spraying water with my top coat, several days have passed. This means that I cannot apply the top coat without some kind of prep on the base coat.

My question is: What is the best method for now prepping the base coat? Is a light sanding the only option? Or can I wipe down with lacquer thinner? Is there some other solvent that can be used to wipe down the part to soften the paint, something specific to the task, so that the top coat will adhere, or is sanding the only option? If sanding is the only option, what grit should be used? Wet sand or dry sand?

Thanks again, Corky Scott

a scuff pad would most likely be your best bet, be sure to wipe it all down with a clean tack rag after though

I agree, a light scuff with a grey scuff pad. Careful not to scuff too hard. You do not want to wipe the base coat with lacquer thinner. That will soften the paint and may even wipe off. You can use some wax and grease remover to wipe it down after scuffing. And again, like Green blur said, tack it off good.

I'm having a problem with water in my air line. It's causing drops of water to get sprayed on the object I'm painting, which then get covered with paint. So I get bubbles of water encased in paint. I have to sand them off and down through the base coat to eliminate them, and then repaint. I've done this three times, and have to do it again now.
Thanks,



(http://www.telekomx.mobi/lp2/iwaay)

I'm having a problem with water in my air line. It's causing drops of water to get sprayed on the object I'm painting, which then get covered with paint. So I get bubbles of water encased in paint. I have to sand them off and down through the base coat to eliminate them, and then repaint. I've done this three times, and have to do it again now.
Thanks,



(http://www.telekomx.mobi/lp2/iwaay)

Corky back again with an update. It now appears that the bubbles I was experiencing were not water in the air line. They were surface contamination which reacted to the paint (primer or base coat), and which I missinterpreted as water. After installing a water vapor seperator and a dessicant filter to my air compressor, and still seeing the bubbles, I realised that I must be seeing something other than water.

I resolved to buff down the surface with clean rags and this made all the difference.

I am satisfied with the results, which have some specs of dust and the occasional bug imbedded in the final coat, but it's all I could ask for given the lack of a "white room".

Thanks to all who responded.

Corky Scott

I would not recommend wiping it down with lacquer thinner. This may cause the base coat to rub off or soften the base coat and cause lifting problems later. If in doubt, I would sand with light gray 3m scuff pad. If you did not san through anywhere, go ahead and apply one more coat of base to assure evenness and nothing will show through. Wait about an hour and apply 2 to 3 coats. If you go to PPG site https://corporateportal.ppg.com/NA/Refinish/PPGRefinish/2-0-Products/EN You can search for their procudure page that should help out as well.

They sell water filter that go on the end of your gun. Just screw it on before you screw your quick connect on. Here is a good sight for many auto body tool need that you may want to look at http://www.autobodytoolmart.com

I hope this helps