I have finally got a technic to fill pin holes in one shot that I will share with the group.

1. Sand your part with 220 paper.

2. Wipe down with pure Alcohol not thinner or prime wash or acetone.

3. I have a large needle (4 inches) and have flattened the point just a bit.
    At ninety degrees lightly push the needle into each and every pinhole and twist.
    (this opens and scores the pinhole)

4. Wipe and rub in the alcohol again, very wet, blow dry with high pressure.

5. Mix a small batch of automotive clear and brush on the affected area. (a good thick coat.)

6. Now with a gloved finger rub the clear in with circular motions. (be aggressive)

7.Now brush another coat of clear on right away. Wait 10 minutes and brush on another coat with what you have left over.

8. I then put the part in my hot box at 110 f over night.

9. Flat sand with 220 grit. BANG the pinholes are ALL gone!

10. clear again with your spray equipment and you are ready to wet sand and compound.

NOTE: I have posted this technic because it works. I used to have to go over a part sometimes 4 times to get rid of all of the pinholes.

If you are a professional Auto Body painter this will sound barbaric, but you can't argue with success.

Hope this helps.

Fred






  

I have heard this from an experienced guy before, he used to rub some sort of clearcoat with his fingers into the opened up pinholes. Never actually tried it myself, it's good to get some confirmation.

Regarding the alcohol, I assume because it's less volatile than acetone which evaporates too fast. Fred is literally washing the gunk out of the pinholes with the alcohol and compressed air. More aggressive solvents might attack the sanding dust too much, making it swell and get trapped in the pinholes?