Is a wet sanded 1500 grit finish too fine for a clear to stick?

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danford1

Is a wet sanded 1500 grit finish too fine for a clear to stick?
I'm painting a car and ran out of the PPG 2021 clear I was using. Would like to try SPI, probably Universal (open to suggestions).
The PPG was wet sanded with 1500 grit to remove any orange peel it had. How rough of a surface does a clear need to stick to?

Danford1
 
When I was still self learning paint jobs I did a 1500 sand and enamel job and it didn't hold very good. Didn't flake off but it wasn't very durable either. I know guys that do it but I feel more comfortable with 1000 grit.
 
There are actually three answers here;

Acrylic urethane will stick but not be real strong as Brad pointed out.

Polyurethanes with 1500 you are at about 97% adhesion and that is excellent.

High solids also will do better them medium solids by about 35%, on average.
 
What grit should I use?

Barryk;324 said:
There are actually three answers here;

Acrylic urethane will stick but not be real strong as Brad pointed out.

Polyurethanes with 1500 you are at about 97% adhesion and that is excellent.

High solids also will do better them medium solids by about 35%, on average.
Click to expand...

What grit should I use?
Is SPI universal clear a polyurethane?
Is PPG 2021 a polyurethane?

Thanks.
Danford1
 
Usually between clear sessions i use 400 and sometimes 600 but not too often. You dont haveto use something as coarse as 400 but it really gives a flat finish where the finer grits dont.
 
Thanks Barry. That makes sense with the enamel job. I could flake it pretty easy with a fingernail. Every since then I've been shy of 1500 for finish work.
 
I was not endorsing the 1500 final sanding at all and do agree with the rest of you 400-1000 is much better.

Just answering his questions.
 
In the collision world we do alot of blending, we use 800 grit for panel preperation to be blended into with a first coat of clear adheasion promoter. Panels that will need sealing we use 400 grit for max adheasion. I dont recomend 1500 grit for its etch is still too fine.
 
A lot of collision shops when say blending a door will use a gray scuff pad and depending on brand will leave about an 800 scratch, never really seen any problems with this.

Universal with one coat will cover 320 dry, just for info.
 
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