What Causes Paint Blistering And How to Fix It? – AutoBody Q&A

Thank you for joining me live. Tony here from LearnAutoBodyAndPaint.com giving you some tips on “How to Fix Paint Blistering on your Car” -Don’t forget to LIKE and SUBSCRIBE to my YT channel for more videos and get great information to help you with your own custom painting! And also, check out the LearnAutoBodyAndPaint VIP Program to learn more about DIY auto bodywork and paint.

QUESTION: I did my first paint job for restoration on a 1971 Porsche. After a few months have some blistering. What is the best way to correct this? It is a solid red. 

So the reason for blistering is the air in your Bondo. Maybe it was wet or maybe you had pinholes in a certain area that wasn’t sanded correctly. Blistering usually happens over body filler. 

Did you get blistering over body filler or over just other areas of the car?

The best way to fix it is to grind them out, if it’s a big blister or blisters you want to grind them out. And if you have body filler underneath, I would actually grind everything out. that’s what I 

Blistering happens over body filler, glaze putties, and filler material because of air and improper adhesion with the filler and the body. The glaze in the body, the glaze, and the primer. So whatever you did there, maybe you didn’t sand for your glaze putty to stick well.

it’s like a cavity when you go to a dentist, and if you have a cavity, they grind it all out. And so the number one thing is you want to clean it out/take out. If there is body filler or glaze putty, you’re going to want to open it up and take that whole area out.

Not just the blister because if you have a blister that big you probably have putty around it a little bit more. So take all of it out and make sure it’s sanded.

I don’t know how deep it is, it’s hard for me to tell you without looking at the project. But if it’s a deep area that you did, you might want to body fill it instead of glaze. 

QUESTION: For rust holes, do you always weld new sheet metal, or do you also use fiberglass/filler at times? if using filler, how long did it take you to get good at it?

So when it comes to rust holes, it depends on your end goal. Are you looking to get out a premium project? You know, and do a good job at it, or are you looking for a wham-bam thank you, ma’am. type of job, because it depends.

Sometimes you’re on a budget, you’re going to sell the car, you don’t care. You just want it to look good. You patch up holes or whatever, you put a nice paint job on it and you sell it. I’ve done that many times. People do that many times, it depends on your project. 

Do you want to do a good job on it? Then you could patch holes with fiberglass. There’s nothing wrong with that.

The number one thing is treating your rusted areas with a Naval Jelly or Rust Inhibitor, or vinegar-water solution 50:50 which works well. You could use white vinegar, distilled white vinegar 50:50 with water, put it on a rag, just touch those areas after you grind it down -that way you can cut the metal out. You can cut the rusted area out if you want to. 

It’s not really not needed if you’re going to patch and weld metal on top of it. As long as you kill the rust you can weld on top of it. So people want to cut it out. You could go that way as well. It really depends on what you want to do. 

If normally with larger holes, I like to use sheet metal and a spot welder. Literally, spot weld sheet metal over the metal.

QUESTION: What clear coat do you recommend? 

if you’re looking for an inexpensive good clear coat, check out Finish1 by ACME. This is the one I painted the bike with. It’s a very good clear coat. And you can pick up there less than 100 bucks about 90.90 bucks. It might be cheaper where you are. I’m in Hawaii so things are a little bit more expensive.

-Tony