Paint Peeling Repair | Paint Gun Settings | Best Sandpaper Grit and More Autobody Q&A

As an automotive painter, you know that a perfect paint job is a key to making a car look its best. But even the best painters can run into problems from time to time, like water spots, paint peeling, or getting the perfect paint gun settings and sandpaper grit to use. In this blog post, we’ll take a look at some of these common problems and suggest some solutions so you can keep your cars looking their best.

QUESTION: What grit do I sand off the current paint on a vehicle and do you recommend sealing the entire body first before doing a basecoat?

If it’s pretty bad like that (photo on the right), I want to use 150 sandpaper grit for something like that because it’s going down through to the primer and metal to basically feather everything out. if it seems like while you’re sanding the edges down and it keeps peeling and it sands off easily, you pretty much want to keep sanding.

Basically, take the whole thing down to metal like do the whole trunk or do the whole door. Do the whole because you want to get rid of that bad paint because it already has bad adhesion to the primer to the metal. I would want to go down and then I use an epoxy primer to go over that, followed by a 2k filler primer.

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You could even use a DTM primer which is direct to metal, a good primer as well. And some regular 2K filler primer. (I’m using EGC and have been using these guys for a while) it doesn’t say DTM but it’s pretty much DTM because if you look at it, it says you can go direct to metal so DTM means direct to metal.

And then you could just put that on and then block it out, and you’re ready for paint. This also acts as a sealer or a good foundation to put a base coat on. So you don’t necessarily always have to put sealers on it.

I do use a 1k sealer at times if I’m prepping my final stages, and I have a little metal showing at the end when you’re pretty much ready for paint, you got metal. This is a 1k sealer, you just shake it up, mix it up, strain it, and just spray it right on over the metal or some of the body filler, and then you put your base coat right on top of it. You don’t have to sand it or anything.

So if I use a sealer, this is the only sealer that I use. They have other sealers that use to spray the entire vehicle but it’s not really necessary. Unless you’re totally anal, you want to get the best possible job. You still can get the best possible job by avoiding a regular sealer stage. 

if it’s bad, you can go to 150 but if your paint is okay and if you’re sanding over paint that’s already shiny and looking good with good adhesion, you basically just need to scuff it down with like a 400 grit and you can spray base coat right over. You can spray any color base coat right over that if you want to because you got clear coat on it. You could just sand that with 400 sandpaper grit and put a top coat right on top of that.

QUESTION: 2015 corolla factory paint job peeling off to primer do I need to spray primer to repaint or paint over the existing primer?

I would definitely just reprime it. Sand down to the primer, scuff up that primer,or maybe even take it off. But I would definitely reprime using a good 2k filler primer, something with DTM maybe, and recoat it, sand it down, block it and then paint right on top of that. And when you’re sanding that you could use anywhere from 150 sandpaper grit to 220 grit so you’re not wasting your time and sandpaper. You want to get a coarser grit to just take it down. Instead of spending all day playing with it.

QUESTION: Should I rub base black before I clearcoat?

As long as it looks good, I would just recommend tacking it down. Just tack it, make sure the dust is down, I would only sand or wet sand if you have some dust that’s wedged in there, that when you feel it you got a little bit of dust here and there, that’s the only time I would just rub that down with like 600 grit. But then if you do that, you might just want to just put a new fresh little light spray of the black base back on that so you could clear coat over it.

QUESTION: Do I set up gun pressure by the max operating pressure in the manual or use the suggested pressure recommendations that came with the paint/primer?

I recommend a wide-open fan, a wide-open air inlet. Some guns have them (air inlet) on the bottom, some guns have them in the back. This is your main air so you could literally lower your pressure coming out of your gun from here. You always want to keep your main open all the way.

And then you’re going to be adjusting your air with your regulator. Make sure this is open(air inlet) all the way. Then you squeeze, the air is going to be coming out and adjust it (regulator) 25-26 PSI for the basecoat, 26-27 or 28 pounds with clear coat. 

If you want to avoid orange peel, it’s basically gun settings. I would recommend the medium-grade gun. This is a medium-grade great gun, or you can spend $1,000 or $800 and get a SATA, it doesn’t matter. A good gun, the distance from the panel is very important and speed flow. Those are the three main things to get very good paint jobs. 

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But another main thing is lighting(check out the GUNBUDD Ultra Lighting System), being able to see what you’re doing. Because if it’s dry or wet or what you need to be able to see what you’re doing to get non-orange peel finishes, that’s the secret to getting a non-orange peel.

Having a medium-grade good gun, not a cheap gun because it’s just not going to atomize the way you want and the fan pattern is not going to be even. Cheap guns- sometimes spray heavier in the center, less on the outer sides, or heavier on the outer fan, not enough paint in the middle, that’s where you get dryness, uneven paint, or orange peel. So hopefully that helps.


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For more helpful links:

The Three (3) Ways to SAND: Wet Sanding VS Dry Sanding Plastic Parts – The Pros and Cons!

How To Sand Your Car For Paint: Wet and Dry Sanding Grit Using DA/By Hand || Autobody Q&A

Primer, Base/Clear Spray Gun, Sand to Bare Metal or Not? Causes of Orange Peel? | More Autobody Q&A

DEMO: How To Use a Stud Welder and Pull Out Dents FAST

SANDING and BUFFING – How Long Should I Leave Clear Before Buff??

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