The exterior surface of my metal insulated garage door has some bubbling of paint. Looking to the forum on advice on the best way to adjust. The bubbling is not in one spot. I was thinking about using a palm sander. Just not sure if that is the correct action to take. If so, what grit sandpaper would be good.


Thank you in advance for your feedback!

Vinny

I would just do the paint repair the same way it's done on cars. D/A with 220 at first, then 320 and then 400. After, prime and paint the whole garage door.

Does the door have an embossed wood grain print in the metal panels?

Maybe related, I always wondered, if you paint an installed door in a closed position, does it want stick to together, and not want open when the paint is dry?
And the solution is?

Spent hours doing our old garage door before the wife wanted to change it to a newer design. It was the one with the 5 or 6 shorter rectangle insets (or whatever they are called). It did have some texture to it, but not much. I sanded, TSP wipe, and then used a quality outdoor primer and paint. To keep it from drying I painted the top section first and got into the crack a bit and painted the second section. When I was close to the joint, I would roll the door up a bit so the joint was open. I did it in 2 days. Top 2 panels one day and bottom 2 the next day. Did it in the summer so it would dry pretty much that day. It did stick a tad, but not enough to keep the door from opening. If I were to do it again, I would let it dry for a few days before moving it again. Didn't want to leave the door open all night when I painted it.

I paint a few of the sections cracked open. Paint dries fast in.the heat here. Then dp.the rest.
As I am able to get Inside the sections whole open. It was white before and now a light tan..
I used a brush in the cracks and a small 6 inch roller on the sections it was good quality paint from Val Spar (PPG) Custom mixed to.matcj the vinyl siding on my home

Yes, the metal garage door has the grain texture. It also has the individual squares as depicted in the photo below. There has to be roughly 4-layers of paint on the door. Some people have recommended thinner or an 80-grit sand paper.

If its been painted a few times you will always have trouble with it lifting. I completely stripped mine to bare metal using a chemical stripper. Was pretty easy to scrap the paint off. Used a good metal prep primer (Galvinized) and followed that with the Behr Paint and Primer in one offered by Home Depot and its been on for the past 10 years with no signs of lifting or peeling and still looks like brand new.