Gelcoat Process

M

marz831

Location
FL
This has been discussed pretty extensively but i want to make sure I have the process down.

I want to gelcoat the bottom of the ski, here's what I was going to do:

1. Prime with a polyester based primer (I have some repairs done with epoxy which the gelcoat will not adhere to properly)

2. Sand with 220

3. Brush on gelcoat (seems to be a PITA to spray) Should I use rollers or brushes? What type?

4. Wait for it to partially cure then spray with PVA

5. Sand/wetsand and buff

If I can get a good enough finish, I may just gelcoat the topdeck too.
 
Mark44

Mark44

Katie's Boss
Location
100% one place
Get the spray gun from US composites they are worth it and spraying is very easy we do it on molds. You spray right from the mixing cup.

Why do you put PVA on top of the gel coat? PVA is a mold release and washes off with water?

I have only done molds not hulls.

Mark44
 
RMBC Freeride

RMBC Freeride

Vintage
Site Supporter
Location
Pueblo, CO
What kind of ski? Gelcoat will not adhere well to SMC. I suppose you could put a coat of epoxy first and then the Gelcoat, but you would just be adding weight, time and cost to the process.

How about Paint?
 
M

marz831

Location
FL
I have no problem with doing paint, just thought the gelcoat would be more durable.

RMBC Freeride said:
What kind of ski? Gelcoat will not adhere well to SMC. I suppose you could put a coat of epoxy first and then the Gelcoat, but you would just be adding weight, time and cost to the process.

How about Paint?
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M

marz831

Location
FL
There was another post saying that gelcoat does not air dry very well and spraying PVA will help it to cure.

Mark44 said:
Get the spray gun from US composites they are worth it and spraying is very easy we do it on molds. You spray right from the mixing cup.

Why do you put PVA on top of the gel coat? PVA is a mold release and washes off with water?

I have only done molds not hulls.

Mark44
Click to expand...
 
RMBC Freeride

RMBC Freeride

Vintage
Site Supporter
Location
Pueblo, CO
True about the PVA for curing the gelcoat, but IMO Putting Gelcoat on a ski as a finish is a waste of time and effort. Besides that, its has to be thick to be sandable which translates to more weight on your hull. Also, gelcoat is not as flexible and tends to stress crack when flexed
 
RMBC Freeride

RMBC Freeride

Vintage
Site Supporter
Location
Pueblo, CO
oxnard111 said:
gel coat will not adhere to epoxy. only poly
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True - if you are spraying it in a mold before laminating with poly. But for repairs or top-coating it will adhere nearly as well to cured epoxy as it will to cured poly... its a mechanical bond, not chemical at that point.
 
Mark44

Mark44

Katie's Boss
Location
100% one place
I see, never sprayed gel coat that I didn't layer on top of with glass.

I learned something new Yea.

Man that hull would be an azz load of wet sanding to get a a nice finish, I would also recommend painting or leaving as is they all get beat up anyway.

Mark44
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
There is no finish I know of more durable than gelcoat,polyurethane damn sho is not more more durable,gelcoat is easy to spray but hard to finish,the trick is to either mix in duratec clear 50/50 with the gelcoat on the final coat or mix in smoothie leveling agent in every coat,it evens out the gelcoat and minimizes the sanding involved in finishing.
 
crammit442

crammit442

makin' legs
Location
here
wedoseadoo said:
There is no finish I know of more durable than gelcoat,polyurethane damn sho is not more more durable,gelcoat is easy to spray but hard to finish,the trick is to either mix in duratec clear 50/50 with the gelcoat on the final coat or mix in smoothie leveling agent in every coat,it evens out the gelcoat and minimizes the sanding involved in finishing.
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All of this is true!
 
McDog

McDog

Other Administrator
Staff member
Location
South Florida
I went to a boat repair/paint shop today and talked to them about this. I was looking for a ployester based primer because that is what USComposites recommended. They told me that ANY quality primer would work fine.
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
mcdog said:
I went to a boat repair/paint shop today and talked to them about this. I was looking for a ployester based primer because that is what USComposites recommended. They told me that ANY quality primer would work fine.
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They are full of bullsheep,pardon my French, either use polyester primer or two part epoxy primer anything else and you are just asking for trouble,Also it needs to be at least 220 grit sanded to give the gelcoat something to adhere to.PS this stuff is not cheap so the learning curve can be quite steep if you screw something up,gelcoat prices are about $80.00 per quart for a good ISO grade gelcoat,the duratec clear is about $60.00 per quart,there is also MEK which actually is cheap and styrene which is fairly cheap also and you need PVA fairly expensive or wax additive to add to the gelcoat also fairly expensive.
 
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McDog

McDog

Other Administrator
Staff member
Location
South Florida
wedoseadoo said:
They are full of bullsheep,pardon my French, either use polyester primer or two part epoxy primer anything else and you are just asking for trouble,Also it needs to be at least 220 grit sanded to give the gelcoat something to adhere to.
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Well where do I get the stuff? I've driven all over town looking for it to no avail. I still need to do my engine compartment.
 
McDog

McDog

Other Administrator
Staff member
Location
South Florida
I guess you gotta call them? I didn't see polyester primer listed. Thanks for the hook up though, IZA HOLLA AT 'EM TOMORRA!
 
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