Painting over gel coat

Emerger

Petty Officer 3rd Class
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Oct 29, 2006
Messages
96
I guess the title says it all. Any tips, tricks, pros, cons on painting over gel coat? Is it a good idea? Disaster waiting to happen?

Thanks
 

Bondo

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70,465
Re: Painting over gel coat

Nope,..........

Just like Painting a Car,......... Corvette if you will........

I prefer 2pt. Ureathanes..........

It's All in the Preparation...........:love:
 

Tail_Gunner

Admiral
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Jan 13, 2006
Messages
6,237
Re: Painting over gel coat

bond-o said:
Nope,..........

Just like Painting a Car,......... Corvette if you will........

I prefer 2pt. Ureathanes..........

It's All in the Preparation...........:love:

As stated above with one exception. Gel coat is as soft as balsa wood and using any mechanical sander should be used with a lot of care. ..:love: Think of like this, your polishing a glass mirror to perfection thats smooth as glass and you will be pleased.

80 grit cuts the surface quite well and you ready to paint.
 

stevieray

Lieutenant Junior Grade
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Jul 18, 2006
Messages
1,135
Re: Painting over gel coat

Also remember that you have to remove all the wax - once before sanding & once after sanding. Use a good wax remover like DuPont Prep-Sol. Leave any wax on there & the topcoat will probably be the disaster you're talking about.
 

croSSed

Petty Officer 1st Class
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Jun 13, 2005
Messages
249
Re: Painting over gel coat

Isn't it also true that most of the time you don't need to use primer? If you get a good rough sand job on the gelcoat, and get all the wax off, the color coat will stick to it nicely. Is that true, or do you need to prime also?

TG
 

Tail_Gunner

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Re: Painting over gel coat

stevieray said:
Also remember that you have to remove all the wax - once before sanding & once after sanding. Use a good wax remover like DuPont Prep-Sol. Leave any wax on there & the topcoat will probably be the disaster you're talking about.

Agreed cleaned first the sanded then primed and yes priming is ness.
 

andy6374

Lieutenant Commander
Joined
Aug 4, 2005
Messages
1,617
Re: Painting over gel coat

Agree on all the above advice.....except

Gelcoat soft???

You need a grinder to get thru gelcoat and down to glass. You would be there forever if you tried using sander.

Gelcoat is used because it is a hard, durable surface.
 

Scaaty

Vice Admiral
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May 31, 2004
Messages
5,180
Re: Painting over gel coat

Primer is the adhesion for any paint....period
After you get it all sanded down, wipe the whole surface before priming with MEK.
 

neat

Seaman
Joined
Jun 28, 2006
Messages
52
Re: Painting over gel coat

andy6374 said:
Gelcoat is used because it is a hard, durable surface.

...and thats why I used gelcoat and not the paint.
 

Chris1956

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Mar 25, 2004
Messages
27,035
Re: Painting over gel coat

Emerger, Sand the gel coat with gradually finer sandpaper until you get to 400 grit wet paper. You will not get a fine finish with courser sandpaper. The wax will be gone by this time, but wipe the hull with acetone to remove any moisture or oil. Mask the parts you want to not paint. Properly prime and use a two part polyurethane suitable for below the waterline (Awlgrip), or if you plan to trailer, you can use a one part polyurethane (Brightside or any of the other gadzillion brands). Use a light color for hulls with imperfections.
 

Tail_Gunner

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Re: Painting over gel coat

Chris1956 said:
Emerger, Sand the gel coat with gradually finer sandpaper until you get to 400 grit wet paper. You will not get a fine finish with courser sandpaper. The wax will be gone by this time, but wipe the hull with acetone to remove any moisture or oil. Mask the parts you want to not paint. Properly prime and use a two part polyurethane suitable for below the waterline (Awlgrip), or if you plan to trailer, you can use a one part polyurethane (Brightside or any of the other gadzillion brands). Use a light color for hulls with imperfections.

Yikes are you sure of that 400 grit stuff for roughing up the gel? I used interlux prescribed method to surface prep using Prekote: BARE FIBERGLASS: Wipe a small area with a clean rag that has been wetted with Fiberglass Solvent Wash 202. While the surface is still wet, wipe with a clean, dry rag. Continue this process until the entire surface has been cleaned. Sand with 80 grade (grit) paper. Wipe with Fiberglass Solvent Wash 202. Repair surface defects with Interfill Epoxy Filler. Sand surface, wipe clean.

Now after the inital coat of primer yep then comes the 220 and that will take the primer to a almost irredesent glow. (glass like)

Hmm want a tip use a dark primer if your going to a light ext color and vise versa if you going to a dark ext.
 

ondarvr

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Re: Painting over gel coat

I know this may sound wrong to some, but primer is not that important for a good bond on gel coat, gel coat is a very good substrate for paint when using a 2 part PU. On most automotive and truck parts no primer is used over the gel coat, it's de-waxed sanded and then sprayed. If the gel coat is in bad shape, with small nicks and imperfections, then primer will fill them and make it easier to do a good job, or if you need to fill an area, primer is needed so you don't see the filler when the paint cures. I used 2 part PUs for 20+ years painting Swimming pools, hot tubs, boats and many other things and I had ZERO bonding issues going straight over the gel coat (no primer).
 

Tail_Gunner

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Re: Painting over gel coat

I see say's the blind man, So in roughing up the gel do you use a heavy grit, medium or light?
 

ondarvr

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Re: Painting over gel coat

Depending on the paint and quality of the sand paper 180 will normally work, but I do go finer if I need to. The coarser the paper, the better the bond.
 

croSSed

Petty Officer 1st Class
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Jun 13, 2005
Messages
249
Re: Painting over gel coat

Well, if you have to use primer, how do you clear coat over gelcoat? Is clearcoat different than regular paint? I have a project where I'd like to clearcoat over the existing metalflake...

TG
 

ondarvr

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11,527
Re: Painting over gel coat

The problem you run into when putting clear over metal flake is that if you sand it enough to get a good bond you can sand through the clear gel coat on the surface and into the flake. If you sand into the flake it can look blotchy and uneven. Most people use too fine of a grit for it to get a good bite, or too coarse of a grit and don't thoroughly sand it leaving glossy areas, then they don't clean the surface very well, just poor prep in general, so it starts to peel in a couple of years.
 

Scaaty

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5,180
Re: Painting over gel coat

This is better than an oil argument. Why don't you Google "How to...blah, blah", and get a REAL answer...
 

Tail_Gunner

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Re: Painting over gel coat

8) Seem's to be pretty simple to me

1. acetone wipe cleaning of any residues.
2. sand down the finish with 180 if painting on gel
-----------------------------------------------------------------------
1 acetone wipe cleaning of any residues
2. sand down with 80 grit if using primer first ( or any grit you wish)

----------------------------------------------------------------------

There are two types of finishe's tech's being talked about here, that being shooting directly on gel (final paint) and in that situation fo course youd want a finer grit. Secondly shooting a primer on first and follow the mfg's guide line's for creating a paintable surface, as already stated a rough surface creates a greater bonding .................8) I dont see any argument here ?
 

bobboater1

Seaman
Joined
Nov 10, 2006
Messages
57
Re: Painting over gel coat

i painted my buddys 21ft regal with interlux boat paint 20 yrs ago just sanded preped . wiped off with actone and after 20 yrs it looks like it needs buffed..i would never think it would have lasted so long he never took care of it..prep means alot
bob
 

Scaaty

Vice Admiral
Joined
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Messages
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Re: Painting over gel coat

I dont see any argument here ?

If its in a forum at IBoats, and it comes out of a can, it might not look like an argument, but I can't think of any other word to describe "disagreement"! 8) :devil: :| :}
 
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