Gelcoating prep.

[PeteyD]

Hi guys I'm finishing up a transom replacement and have some gelcoat I'm gonna use, I just have a few questions.

1. Can I apply it to the biaxial or should I lay down csm?
2. What's the percent of acetone to volume of gelcoat for thinning?
3. Do I apply two coats and can I add airdry to the final coat?

I have a general understanding of sanding prep and what not but any more tips would be great. Thanks guys

 

[Yacht Dr.]

Re: Gelcoating prep.

Hi guys I'm finishing up a transom replacement and have some gelcoat I'm gonna use, I just have a few questions.

1. Can I apply it to the biaxial or should I lay down csm?

As long as the glass is prepped you can apply it to your biax ( though you might have hairs of glass that might raise up on you ).

2. What's the percent of acetone to volume of gelcoat for thinning?

Depends on the gelcoat and application .. are you rolling/brushing or spraying ? Spray is normally about 25% reduction.

3. Do I apply two coats and can I add airdry to the final coat?

Two coats is not enough .. I dont know what " Airdry " is .. but I would not use it.
You have 4 coats of gel .. sand and buff.

YD.

 

[ondarvr]

Re: Gelcoating prep.

#1 If you don’t plan to finish it as a smooth surface you can just use gel coat over the biax, if you want it smooth, then depending on the exact biax it may add too much texture. You don’t want to sand on biax to smooth it out, if you do you will be removing fibers and will reduce the strength, in this situation you would use a mat over it for some meat to sand on.

#2 You don’t want to add acetone (at least not much) to thin Gel coat. While it will reduce the viscosity it can also create other problems that may show up later. Color, gloss, water resistance, UV resistance, crack resistance and other things can be affected.
If you need to thin gel coat there are products sold for this purpose.

#3 It may take more than two coats, it depends on the surface, color of the gel coat, how smooth you want the surface, plus other things, but yes add airdry to the final coat.

You asked about thinning the gel coat, this is only done when spraying it, if you are only recoating the inside surface over the glass it is normally rolled or brushed and no thinning is needed. So how do you plan to use it?

 

[PeteyD]

Re: Gelcoating prep.

Thanks for the info guys. I was told i should be using styrene to thin the gelcoat is that the better way to go? I was planning on spraying, atleast the outside skin of the transom where i have repaired cracks from the motor. I guess il probbly roll on the inside if thats better?

 

[ondarvr]

Re: Gelcoating prep.

Styrene has its own issues, so its not really recommended either.

Both styrene and acetone can help it spray better, and if used in small amounts (less than 5%) may not cause any noticeable problems. The problem is as you add more the affects start to make themselves known, it may look fine for a while, but over time it may start to show the signs of the lower physical properties.

There are Patchaid products sold that are formulated to reduce the viscosity and not have as many adverse effects as other solvents.