The Stovebolt Site Forums The Shop Area Paint and Body Shop What causes these pin holes in paint?

Don't know what else to call them besides little pin holes. Not clear to the primer, but in a couple of spots I have what looks like little pin holes. Hopefully you can see in this.
I could only get them to show in the picture when the sun is on the spot so that is what you are seeing so brightly. I saw a couple of places like this when I was painting and flowed more paint on and they disappeared. Am I just putting it on too thin and causing this? I will try buffing them out to see if that takes care of it but would like to figure out the cause before I screw up a big piece. This is PPG DCC solid color.

Dennis

If they are real tiny pin holes they are likely solvent pop, which is caused by not enough time between coats for outgassing to occur. Subsequent coats trap the solvents in, where they will cause that damage once they finally break through. Urethanes are especially prone to this, the flash times must be followed religiously. Keep in mind, a "home booth" with inadequate air flow will adversely effect the outgassing where you'll need to add some time onto the mfr's recommended flash times.. Cooler temps, same thing.

Thanks Robert. It says 10-15 minutes and I waited about 20. It was 68 degrees using solvent for 60-70 range. Not much air flow though as you say. I'll try giving it a bit more time next time.

Dennis

Could also be fish eyes, which are caused by oil or silicone contamination of the substrate. I've torn my hair out over those when refinishing some doors for my house (the wife wanted gloss ).

Here's some info that should help you figure out a solution.

http://www.searchautoparts.com/abrn...iques-how-approach-commonly-seen-defects

Yup, fisheyes. Be sure to use a good wax & grease solvent prior to painting. It's also a good idea to clean a surface prior to sanding. I have seen surface contamination driven into sanding scratches by the sanding process. If you don't want to by a large quantity of a commercial wax & grease remover for a small job, common mineral spirits will do a good job for you.

I would not agree with using mineral spirits. Mineral spirits is oil based and will cause fish eye's.... I gallon of wax and grease remover is probably $30. Small price to pay to not have any issues....

From the picture it looks like fish eye's. Do I need to fly out there and help out paint that thing? Looks like a beautiful green for an old truck!

I did clean with DX330 but maybe did not do a good job. One thing I was thinking about is that I had it wrapped in some packing material. Not sure what you call it but it is about 1/8 thick foam. Maybe it has something on it that my paint is not happy with. Anyway, won't use that again just in case.

It may take me a gallon or so more than it would for someone that knew what they were doing but I'll get it. Especially with the help from this forum. I can always sand away the mistakes and shoot it again until it is right. Glad you like the green. That is a story in itself. Choosing the color took me a long time. Kept finding other things to do so I could put it off.

Dennis

Dennis, I have been painting for over 25 years and I still have to redo stuff every once in a while. My father has been a painter all of his life and I still seek advice from him. My number is listed in my signature and if you have any questions I'll see if I can help.

It's great that you are keeping at it until you get it. Patience is important and sometimes we just get in a hurry and screw things up....

I would suggest getting all the practice in on the panels that bolt on. Even on the underside of the hood, before the top. Get used to it before the cab.

Fish eyes for sure. All great advice from bolters. One more thing to check is oil contamination from your air supply. My guess is since the rest of your panel looks ok, a small blast of contaminant (oil from the compressor motor) got into your airline. Are you using any type of filters before or at your spray gun? The small round plastic filters that screw onto the fitting on your gun are a only a few bucks. Good luck, digg'n the color!

Must disagree. I've used it many times without issue. Commercial wax and grease remover is petroleum based as well. One additional tip. Wipe whatever product you choose to use on with a dripping wet rag and wipe it off with a known clean rag before it has a chance to dry on the surface. If it dries on the surface all you're doing is moving the contamination around.

I'm using a CamAir QC3 filter. Maybe I'll add one of the small filters at the gun. Can't hurt.

Dennis

Another possibility is paint on a finishing putty surface. Finishing putty will always have pinholes in it so that is why a high build primer is advised. If you sand through the primer you can have a result similar to yours so reapplying primer us highly recommended.
Another possibility is primer shrinkage. If the high build primer is applied and allowed to cure then sanded, it can shrink into the pin holes of filler and or finishing putty afterwards. The solution here us to leave primed panels unsanded for a week allowing all solvents to leave. Priming over filler with heavy scratches will also show up as a failure in the paint.

I hadn't heard that about finishing putty Darcy. I haven't used any on this project though. I just use Evercoat Rage Ultra. It is so smooth I don't see a need for the finishing putty. What do you consider heavy scratches?

Dennis

Rage ultra is a very nice product but still needs a finishing putty or glaze.. like Metal Glaze. The talc and resins used are very fine and don't require you to reshape the panel. Just a super thin coat is all you'll need to fill pin holes and fine scratches in your filler.

Read the P sheet or technical data sheet for the products you're using. The high build will tell you grit ranges as well as the Evercoat products.

You can sand with too fine of a grit or too coarse. The manufacturers will be the best source of that information.