Being European, I still did not master the whole "ounces and tbs" conversion thing (30 years later...) so i think I messed up the proportions of the gel coat paste, pigment, and hardener. Regardless, the gel coat patch never really cured. It's dry and not tacky, but it never hardened (i.e. it can be scoured with a fingernail). Unfortunately, it's too hard to scrape and too soft to sand it of. The area is pretty big (two hands, about). Any thoughts? It's on my son's Opti, so it's not that important, but I want it to look decent. I thought about committing a cardinal sin and simply over lay it with a layer mixed to the correct proportions. The thought being that the contact with the hardener in the top layer would harden and help bonding both layers. At worst, I'll have to redo the whole thing. I KNOW you shouldn't be doing it this way, but is there a chance of success if I do?
messed up gel coat repair
- Thread starter Piotr
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I know exactly how you feel...
That's why I prefer the percentile ratio method ;-) Or metric proportions. Needless to say, as justsomeguy said, if the gelcoat did not have any paraffin in it, the surface will never set properly. Usually one needs to block the air access (with page protector, for example. You may want to try to wash the surface down with acetone, re-activate with styrene and then apply yet another thin coat of gelcoat, sealing it from air this time. Alternatively get small batch of gelcoat with paraffin, known in some places as the topcoat. Otherwise, if your proportions in mixing gelcoat/hardener where off, unfortunately you will have to remove everything and start from scratch :-( I usually go with between 1.5%-2% hardener for gelcoat.
got wax?
AFAIK: gelcote used when the hull is assembled does not contain any wax. and cures after the resin for the next layer is applied.
gelcote used for repair needs: either wax added to the mix, OR, an air sealer (usually plastic) laid over the repair.
if you didn't get wax added, you can try to put a thick plastic bag over the repair.
if that doesn't work, wipe it off with MEK or Acetone, and start over.
my experience is gelcote needs a little more catalyst, than simple polyester resin.
mix up a sample 1st to test... then a 2nd larger batch once you know what to expect.
AFAIK: gelcote used when the hull is assembled does not contain any wax. and cures after the resin for the next layer is applied.
gelcote used for repair needs: either wax added to the mix, OR, an air sealer (usually plastic) laid over the repair.
if you didn't get wax added, you can try to put a thick plastic bag over the repair.
if that doesn't work, wipe it off with MEK or Acetone, and start over.
my experience is gelcote needs a little more catalyst, than simple polyester resin.
mix up a sample 1st to test... then a 2nd larger batch once you know what to expect.
Only to allow smooth finish, and I already knew I would have to sand it any way. So I did not.
Good advice ..... one thing more before you destroy your previous work .......
Always use a 'parting fluid' when doing gelcoat repair ...........................
Obtain and use a "parting fluid" also known as Polyvinyl Alcohol / PVA and simply spray or brush this over your previous repair and let set for a day or two on the surface. This will 'harden' and accelerate the 'cure' of the surface gelcoat.
Once fully cured, you can wash off the PVA with warm soapy water, then 'flat sand' and power buff, etc. the gelcoat. "Always use a 'parting fluid' when doing gelcoat repair to harden/cure the exterior surface that will be buffed/polished".
PVA is also used as a 'mold release' when applying gelcoat to a female mold ... it ensures that the surfaces that touches the inner mold surface fully cures and the part is easily removable from the mold.
example - http://www.jamestowndistributors.co...duct.do?pid=4213&familyName=Polyvinyl+Alcohol
OK, did as instructed on this forum. Put some of the PVA on the gel coat repair. Waiting 4-6 hrs to cure. Will re-read instructions on the gel coat paste. I'll update on the results.
^ interesting about the mix 1:1 then 3:1
I like to use these preval disposable sprayers.
http://www.jamestowndistributors.co...t.do?pid=2155&familyName=Preval+Spray+Gun+Kit
a painter I met used cigarette ashes for pigment.
I like to use these preval disposable sprayers.
http://www.jamestowndistributors.co...t.do?pid=2155&familyName=Preval+Spray+Gun+Kit
a painter I met used cigarette ashes for pigment.
Well, the PVA worked a bit, but most of the stuff is NOT completely solid, just not tacky. Added another patch for the inside - the outer edges are still soft after 2 hrs, but the middle (covered with acetate) is a little better. The danged thing solidifed only after I added half of the hardener. The only issue I can see is that I added too much pigment paste. But I don't see how. Or that I have the wrong hardener somehow.
I need to get more hardener tomorrow...
I need to get more hardener tomorrow...
If its still not cured fully, suggest that you apply a heat lamp but being careful not to let the surface exceed 120°F ... using an infrared indirect thermometer on the surface to monitor the temperature.
• Did you make the initial repair with epoxy, then applied the gelcoat?
• If the initial repair was epoxy, did you scrub / water-wash the cured surface of the epoxy before applying gelcoat?
Polyester gelcoat is INCOMPATIBLE with the 'amine blush' that forms on the surface of epoxy as it cures; the 'amine blush' MUST be removed (scrubbed/washed) or it can retard/prevent the gelcoat from curing.
• Did you make the initial repair with epoxy, then applied the gelcoat?
• If the initial repair was epoxy, did you scrub / water-wash the cured surface of the epoxy before applying gelcoat?
Polyester gelcoat is INCOMPATIBLE with the 'amine blush' that forms on the surface of epoxy as it cures; the 'amine blush' MUST be removed (scrubbed/washed) or it can retard/prevent the gelcoat from curing.
I just read up on amine blush (literally 2 minutes ago). I did not wash the epoxy, but this is a second coat. the first one was from a repair kit and I had 0 problems with it. unfortunately, I used the wrong pigment (with bluish tinge) so i decided to cover it with the correctly pigmented polyester. I sanded the first coat of gel coat down, in places through to the epoxy. The second coat was from the "economy" can of epoxy (as opposed to the repair kit). I think maybe I have a bad can of polyester...
If you thoroughly sanded the epoxy, then youre probably OK on that potential problem. Next time use warm water scrubbing before sanding epoxy onto which you will apply gelcoat.
Also, gelcoat can become 'funky' one year after its manufacturing date.
It has a relatively short 'shelf life'.
If your gel is still tacky, only thing I can suggest is to respray/brush with PVA, cover it with plastic sheet ... and wait a week or two.
Also, gelcoat can become 'funky' one year after its manufacturing date.
It has a relatively short 'shelf life'.
If your gel is still tacky, only thing I can suggest is to respray/brush with PVA, cover it with plastic sheet ... and wait a week or two.
Just read the Evercoat web page on troubleshooting. They list old hardener/epoxy as one of the reasons gelcoat may not set/cure. I'll try the heat lamp trick first. then I'll get more fresh hardener. I'll MAKE it set and get harder one way or the other... oh, wait a sec...
I just had a problem with my gel coat. It would not harden even though it was the finish kind. It is a year old and the wax must not work after that. I put some blue painting tape on it over night and it hardened right up. I will now sand it down to smooth it and then another coat of gel coat with a plastic cover to finish it off.
The tape saved me a lot of work.
The tape saved me a lot of work.
I noticed. I put the acetate over the new patch and everything that was covered up hardened. Also, the temperatures jumped to 83F , which likely aided the curing process.
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