Paint question.

[Lynn]

Any paint guru’s out there? I am strictly an amateur. I have painted lots of laquer over the years, always with excellent results. This is my first experience with urethane. I am painting an old Suzuki motorcycle. Using PPG products, candy apple red over gold metallic with clear coat.

Following the manufacturer’s directions, I painted some practice areas on a metal panel just to make sure I had the routine down. Had no problems. Even had an extra decal to lay on top of the color before putting on the clear. Worked flawlessly.

Painted the plastic side panels with the epoxy primer. Let it cure a week (yeah, I know, overkill), then wet sanded, washed thoroughly, and dried. Blew then off and ran a new tack cloth over them.

Sprayed the first base, gold flake. Came out perfect. Let that dry overnight, gently blew them off to insure no dust settled overnight. Sprayed the red. Took about 5 coats to get the color I wanted. Red looked perfect. No fish eye, no runs, etc. Let that set up for a few hours. Directions say you must clear coat within 24 hours, or else you will have to “scuff” the red before clear coating. Directions say you can clear coat in as little as 20 minutes, but I wanted to wait longer than that since I had put so much color on.

After about 3 hours, shot the clear. Because the color was so fresh, I didn’t clean or prep it in any way, just as I had not cleaned and prepped between the gold flake and the red. Directions call for two wet coats, so I shot it wet. Waited 12 minutes between the two coats. At first, I thought it was going to be perfect, but then noticed a bunch of very small indentations. Maybe 1/32 of an inch to 1/16 of an inch. Almost looks like a bit of fish eye, but not quite the same as what it would look like in laquer. I only dealt with fisheye once time shooting a car with laquer, and solved it by simply wiping the affected area down with a clean, rag damp with laquer thinner. Shot right back over it, and it came out fine. Well, I wasn’t about to do that with the urethane clear, so I just let it dry. Have wet sanded trying to get down to the indentations, but can still see them slightly. I am afraid if I shoot over this again, the same spots will still not “take” the clear, and the indentations will be worse.

I really don’t think it is a contamination problem, as I shot the clear with the same gun (Sharpe HPLV) as I did the color. My compressor is oil free, and I have two water separators in line to my spray hose, as well as a two stage regulator system. I just cleaned out everything the day before. if it were a contamination problem, I would have expected it to surface with one of the color coats. Of course, I could be wrong.

I really don’t want to sand these things all the way back down and start over. If they were metal, I could see it, but plastic....

Two questions. 1. Anyone know what caused this?

2. Can I fix this?
I was thinking I could mix up a very small batch of clear per the directions (4 parts clear, one part reducer, one part activator), then using a match stick, or other very small applicator, fill in each of the little indentations by hand, let it dry and wet sand the piece until it is uniformly smooth? Then clear coat over it?

Thanks for any help.

[SuperNovaSS]

Your plan seems pretty good. Something probably comtaminated the area during the long dry time. Drop a few drops on, let them dry, they hit them with 600 along with the rest of the tank. Then clear the whole unit one more time. That it what I would do. Either that or brush touch the few areas, wet sand, the buff to see what happens. If that doesn't work, sand then reclear.


Hope it works out easily,


Jason

[Stitch]

Could be due to something called 'solvent pop' , it can happen when you lay the paint on very heavy and/or the ambient temperature is too high at the time of spraying or not enough flash time between coats.
The paint skins over before all the thinners/reducer has had a chance to evaporate it then tries to push it's way through the skin causing small bubbles or pinholes to appear. Do the blems your getting look like this ? , fish eye looks like tiny craters and is usually caused by silicone contamination on the underlying surface .

As Jason says your remedial plan sounds good and you probably won't need to apply any more clear coat , make sure it's fully cured though before you wet sand.

[m22mike]

Very likley "Solvent Popping"

read this old thread.

http://autobodystore.com/forum/showt...olvent+popping

http://autobodystore.com/forum/showt...ight=pin+holes

[firez]

I had the same problem so I sanded the entire door with 600 wet paper and let it offgas for a week. I went over the area with 600 after a week lightly and sprayed the door again with no problem. I have heard of the problem also when things are painted in humid weather.

[farone]

It appears that you didn't spray the clear "wet" enough.... The clear will not flow as you think that it would.... If you over reduce the clear a little, about 10%, it will also help this. The second coat will usually fill these in. There is a fine line between too dry or too wet. Lightly scuff the parts, but don't break thru the clear, and recoat.

[Lynn]

Thanks guys.

[Lynn]

Going to recoat this weekend. One more question: Would the clear flow any better shot with a conventional spay gun? Maybe more margin for error. I have an old Devilbiss gun that always worked very well for me, and is still functional. Also have an old Binks #7.

Thanks again for your help.

[Stitch]

Probably best to check the tech sheet from your paint supplier , some modern paints are intended for use with an HVLP gun .

[Lynn]

Tech sheet gives specs for both kinds of guns. I have the correct tips for each as called for by the tech sheet.