gel coat tacky??how long to fully harden.

mrfixit4818

Seaman Apprentice
Joined
Jun 15, 2009
Messages
31
I have a 82 bass boat and the top of the boat is sun baked.its brown w gold flake.I sanded a large section and wiped it with acetone then brushed on some gelcoat and it came out great but the only thing is it wont harden fully.its been 2 days now and its already all messed up from touching and leaning.I mixed the hardener 2 percent like the directions said.can i fix it or do i need to wipe it all up with acetone and use car clearcoat??????help
 

tdrudd87

Petty Officer 1st Class
Joined
May 28, 2009
Messages
288
Re: gel coat tacky??how long to fully harden.

You might have needed to add wax to the gelcoat before applying it if it has firmed up but is tacky on the surface.
 

mrfixit4818

Seaman Apprentice
Joined
Jun 15, 2009
Messages
31
Re: gel coat tacky??how long to fully harden.

Wher do i get it?can i give it another coat with the wax in it?thanx
 

tdrudd87

Petty Officer 1st Class
Joined
May 28, 2009
Messages
288
Re: gel coat tacky??how long to fully harden.

I got mine from us composites, the resin I bought for my resto was unwaxed. Should be able to recoat unless someone says otherwise, that is the point of unwaxed mixtures, so the recoats bond chemically.
 

tboltmike

Petty Officer 1st Class
Joined
Aug 17, 2006
Messages
340
Re: gel coat tacky??how long to fully harden.

Might want to reconfirm your mix ratio. It is easy to get a decimal wrong in those low % numbers.

I'm way out of my field here, but I understand that there are some resins that won't cure in the presense of air. Heard of a case simliar to yours where saran wrap was placed over the resin and it cured. Have no idea of the the type of resin.

The mention of wax reminded me of this case.

Mike
 

willamettejeff

Chief Petty Officer
Joined
Nov 15, 2004
Messages
550
Re: gel coat tacky??how long to fully harden.

I've done quite a bit of gel coating while renovating my boat and I can tell you for sure that un-waxed gel coat will not fully cure in contact with air. Gel coat was made to go inside a mold and then to be covered w/fiberglass thus sealing it from air and allowing it to fully cure.

I have not found the wax additive to be all that reliable in causing get coat to fully cure and according to Tap Plastics they have also found it to be a real hit and miss affair. I now exclusively use PVA (poly-vinyl acetate) as it consistently provides a fully cured hard surface. It is a colored liquid that you just spray with a spray bottle or spray gun over your final coat that seals the gel coat from air. It is also water soluble, so is just removed with a wet towel after the gel coat cures. It is colored to show you where it has already been sprayed. PVA is available from your gel coat supplier.

-- Jeff

PS. You are probably going to have to remove the gel coat you have already put on as it has been too long for another coat to fully cure the original one. I had the problem you have happen on the bottom side of my motor well and finally just had to remove the gel coat and redo it. I had waxed the gel coat the first time and it did not ever fully cure. On the redo I used PVA over the gel coat and it hardened up very nicely.
 

wca_tim

Lieutenant Commander
Joined
May 28, 2007
Messages
1,708
Re: gel coat tacky??how long to fully harden.

as an aside...

gel cures by what's called free radical chemistry. Free radicals react with / are shut down by oxygen. If you don't generate enough reactive species, the gel doesn't cure. You might well be able to get it to cure if you coat with pva and then put a uv light or maybe just in the sun. Light, especially UV light, can form free radicals.
 

jonesg

Admiral
Joined
Feb 22, 2008
Messages
7,174
Re: gel coat tacky??how long to fully harden.

I use PVA as a mold release after waxing, it will form a great barrier for your purpose.
I just spray it with a windex spritz bottle in a pinch..
 

mrfixit4818

Seaman Apprentice
Joined
Jun 15, 2009
Messages
31
Re: gel coat tacky??how long to fully harden.

1st coat is still a little sticky can i leave it on?getting the pva friday,found a local boat place that sells it,can i give it another coat then how long before i pva it?
 

willamettejeff

Chief Petty Officer
Joined
Nov 15, 2004
Messages
550
Re: gel coat tacky??how long to fully harden.

1st coat is still a little sticky can i leave it on?getting the pva friday,found a local boat place that sells it,can i give it another coat then how long before i pva it?

Coat w/PVA just as the gel coat starts to set up. Don't get too close with the sprayer as to distort the get coat surface. Still think you are going to need to remove the first coat as I don't think it is going to fully harden at this point leaving you w/soft gel coat under a hard outer layer. That has been my experience at least.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,525
Re: gel coat tacky??how long to fully harden.

If its still tacky then you're fine, you can go over it. The main concern would be dust, dirt, finger prints or other junk that's on the surface, with clear you'll see it.
 

lmannyr

Master Chief Petty Officer
Joined
Jul 5, 2007
Messages
815
Re: gel coat tacky??how long to fully harden.

Covering the applied gel coat with a thin plastic film will also work. I'm in the process of fixing all the dings and scratches on my rig and this works well. Tape all sides to prevent air from getting in. It'll be dry to the touch within 1 hour, less if heated artificially or placed in the sun.

I also use a hair dryer on high heat for about 5-10 mins, let it cool, then wet sand the top layer.

I've done plenty of my gel coat repairs using both of these methods with excellent results.

One less item on your supply list (pva).
 

nymack66

Petty Officer 1st Class
Joined
Aug 5, 2009
Messages
356
Re: gel coat tacky??how long to fully harden.

You simply add "Sand Aid" to a non wax gel to harden it PVA will work trick is you have to know when to spray it on 2 early no good 2 late ditto .On my Boat I apply multiply coats of no wax gel then the final coat mix with "Sand Aid " this makes it cure to hard finish .
Follow this link and download the PDF very informative stuff and feel free to call them for any questions and yes they will ship anywhere.
 
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