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Wet sanding filler primer

54K views 9 replies 7 participants last post by  50montereymike 
#1 ·
I have finished applying the last application of high build primer.

I plan on wet sanding then sealing (if needed). What grit should I be using 320 then 600?

Any tips for wet sanding curved sections? I plan on using a sanding block but it there something better suited for rounded sections?
 
#3 ·
If you are planning on laying on some color, I would finish wet sand with 600. I am having to re-do the gas tank cover on my 34 because I tried to get away with 400 before the base. I sprayed two coats of base and I still could see sand scratches so I stopped. I have wet sanded it with 600 and will be shooting it again tomorrow evening.

If you have block sanded all those coats I would wet sand with a rubber sanding block or a paint stirring stick, do not use your bare hands. For curved sections I have been using some of that dense packing foam. The stuff is really dense and it is used to support heavy objects during shipping. You can cut it into nice sanding blocks.

Vince
 
#4 ·
Be more specific on exactly what kind of primer you are using. "Filler primer" could mean a lot of things to different people. You certainly don't want to wet sand lacquer. I personally don't like to and don't believe you need to wet sand any primer. If it is a quality 2K primer it is not big deal, it isn't soluable or anything, I just don't find a need.

And no, if it is a quality primer you don't need a sealer. HOWEVER, check with your tech sheets.

Brian
 
#6 ·
I'm with Brian on this. If you have blocked your surfaces twice (and are confident they are flat) there is no real need to block or wet sand the final primer coat.
I am pushing using 3M's soft pad on a D/A for final sanding. I use 800 grit with no issues. This thing works great, it is fast and does an excellant job of maintaining a surface as long as you don't linger.
The other thing is to MAKE SURE YOUR CAR IS CLEAN before you spray topcoat. Wet sanding puts dried and caked residue into every nook and cranny. You have to go over everything with wax and grease remover and a blowgun to remove it all. This is why I stay away from wet sanding as much as possible.
Wet sanding the topcoat is good but, prior to that, all it does is make a huge mess you have to clean up before you can spray final color.
Mark
 
#8 ·
I agree with Bob, wet sanding is not a problem for me either. I do not miss the dust and the mess created is much easier to deal with. I'm going to clean the surface real good anyway before I shoot base. Also I get a far smoother surface wet sanding.

I really do not agree with no final sanding on your final primer coat. I am not that adept at laying the final primer coat down that smooth so I do not have to final sand it.

Vince
 
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