Pinholes in paint mystery

R

Richard Lorenz

Senior Member
After pulling green (Scotch?) tape off of acrylic enamel ( no hardener), there were several pinhole spots a little larger than 1/32 inch diameter. The paint was put on in a heated garage, and allowed to set up for a week in temperatures around 50 to 55 degrees. The holes look almost like they were drilled into the paint. They are not fisheyes.

My guess is that the tape was pulled off too fast and created static electricity discharges that might have created the holes. Just a guess. Anyone else have an idea as to the cause? Thanks.
 
I would agree with grapp, probably solvent pops. If you apply a second and/or third coat to quickly, solvent may be trapped in the bottom layers. The solvent ends up popping through the paint in spots (mine looked like very small volcanoes). I had this happen a couple of years ago with PPG Concept - an Acrylic Urethane paint. Now I wait for a least 30 minutes between coats.
Rusty Nelson
 
I had the same thing once when I used DP-90 and DCC 9000 black to paint my horn. You almost need a magnifying glass to see the tiny holes, so I might leave them and see how it looks after wax it or buff it out a bit. I was told that I probably didn't wait long enough after the DP-90 was shot before I put on the top coat.
 
If a diesel is in the area the exhaust mist that settles on the car will cause small pin holes as the paint dries.
 
Could be humidity blisters in paint.

This is water vapour/mist under your paint from a lousy filtration system and/or a hot overtaxed compressor.

Only time will tell if the whole job bubbles up later on.
 
I once worked in a truck shop and one of the guys was in the paint booth painting. Another employee (later fired) said "watch this" and opened a tube of RTV, gave it a squeeze and set it just inside the door of the paint booth, ruined the whole paint job, looked just like your describing.
 
A lot of things can contaminate a paint job....diesel exhaust, car exhaust, silicone fumes, PB Blaster fumes, a bunch of stuff. You need a dedicated paint area without contamination else you will begin to see all manner of defects on the freshly painted surface. Was the car cleaned at least twice with surface cleaner (specific to the painting industry)? Was it tack clothed with a product specific to the paint industry? Did any cars in the area or in the shop have tire shine on? That stuff is silicone and will outgas and ruin a paint job in 5 secs. Do not keep ANY silicone products in your shop if you ever plan to paint.
 
Maybe it's time for everyone to quit speculating without more information. I sure read it to say the problem was under the removed tape only and NOT all over. If that is the case then most of the responses are on an entirely different page.
 
That happens to me, the tape pulls the paint off, Mostly when the paint is fresh.

pooch said:
Could be humidity blisters in paint.

This is water vapour/mist under your paint from a lousy filtration system and/or a hot overtaxed compressor.

Only time will tell if the whole job bubbles up later on.
Click to expand...
Oh.. so that would explain what goes wrong when i paint things with a tiny compressor.
 
I wonder if the paint bled thru the tape and reacted with the adhesive to soften the under lying paint? Some of the painting tape is for house type paint.
 
I've experienced this with enamel before. If you use a reducer that is too "hot" or fast for conditions you may get solvent bubbles that DO NOT pop the surface, they lie just under the flashed skin of the top coat. They show up if you rip tape or wet cut to remove orange peel. Examine the pits with a 10X magnifier. If they are dull inside it is solvent. Shiny skin inside = dissolved air in the paint mix- a gun setting and/or app. technique problem.
 
I don't understand how you would have tape over freshly painted AE ?? So I don't think the OP was clear enough. Even if the AE without hardener was a month old, I wouldn't want to tape over it.
 
PetesPonies said:
I don't understand how you would have tape over freshly painted AE ?? So I don't think the OP was clear enough. Even if the AE without hardener was a month old, I wouldn't want to tape over it.
Click to expand...

As Marco suggests, we are mostly just guessing, but that is OK, there is other info for other folks as well with the OP question getting bandied about for the betterment of all involved in perusal of a topic on paint dramas.

Pete...maybe the OP was shooting a masked up second colour on the swages?

Again, just speculation.
 
Sounds like Solvent pop to me. If you put tape on the surface and left it for a couple of days, the solvent was trapped under the tape and couldn't get out. it collected and caused a solvent pop. Not using the hardener would slow everything down so that didn't help either. You may find in the future that by not using the hardener you will get a solvent reaction if you have to respray a panel. Not a good thing to do.

The Old Tinbasher. (Do they still make acrylic enamel??? Havent see it here in 20 years.)
 
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