sand paper grit

[T-Bucket Bob]

What is a good sand paper grit to take off the fiberglass gel coat to get the body ready for primer?

Thanks, T-Bucket Bob

 

[2old2fast]

First , you don't want to remove the gel-coat. Use a wax & grease remover to get the surface clean. What grit paper you use depends on what type of primer you plan to use. It would be best to consult w/ a paint supplier/jobber to plan what paint system you plan to use , they will be able to advise you on what grit to use to provide adequate "tooth" for their primer/ sealer .
It ain't like it was in the old days...
dave

 

[RPM]

The gel coat has a wax on it from the mold that the body was made in. That wax needs to be removed before you start any sanding.

 

[Hotrod46]

The gel coat has a wax on it from the mold that the body was made in. That wax needs to be removed before you start any sanding.

Believe this!! I didn't do it (I had never worked with fiberglass before) and had a very bad case of fisheyes in the paint.

 

[choppedtop]

I used naptha to remove any wax from the gel coat. Then I used an air jitter bug with 150 paper(dry/open) to sand the gel coat to give it bite for primer.
Of course there are places that have to be hand sanded also. I would try to avoid going through the gel coat finish if possible. In some places you may have to, so to smooth down a high spot.
Lee

 

[TriodeLuvr]

Back when I did Corvette work, I always finished 'glass and gelcoat with 400 wet/dry. Anything less runs the risk of surface scratches showing through the paint. Never had the primer coat fail, but can't speak to the newer formulations. Like Dave said, it's best to ask the manufacturer.

Jack

 

[Keeper]

I have the steps I went through when I painted mine. Let me track it down.

 

[Keeper]

I cannot find it, but here is what I did: (I did ALL of my sanding wet, to reduce dust)

Wax and grease remover to pull out wax of gel coat
220 grit for initial smoothing of gel coat
First round of filler
220 to smooth things out
2nd round of filler
220 once again
1st coat filler/primer - I used evercoat slicksand as a sprayable filler/primer
320 to smooth primer and get body straight.
2nd coat of slicksand
320 - using guide coat to ensure things are smooth
400 - to remove 320 scratches
600 - to remove 400 scratches - I only went to 600 due to spraying a metallic as was recommended by the paint supplier

Sprayed 4 coats of base to ensure coverage and eliminate any tiger stripes
Sprayed 3 coats of clear as I knew I would be cutting/polishing the clear. (This is where the fun began with orange peel!)

Once the clear cured for a few days:
1500 to knock down most of the peel and there are a ton due to using a faster reducer due to painting in a garage - it was either dirt/bugs or peel
2000 to fix 1500
2500 to fix 2000
3000 to fix 2500

Then came the Meguires 105 on a orange pad
Meguires 205 on a white pad
Meguires 205 on a black pad

Sealer
Wax

I am sure I could have skipped some steps in there, but it was my first time painting and after the sticker shock of paint supplies, I was not about to cheap out on my labor and sanding.