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ContinuousWave: Whaler Repairs/Mods
Sea-Fit Gelcoat Patch
|Author||Topic: Sea-Fit Gelcoat Patch|
posted 06-17-2002 01:00 PM ET (US)
Has anybody had success with this stuff?
I bought a small tube of "Off White" for $8 at West, applied it on some gelcoat dings, and it doesn't seem to harden. I even put some scotch tape over it thinking it might need an air free environment to dry. I can still put a gouge in it with my fingernail.
Am I doing something wrong here?
posted 06-17-2002 03:06 PM ET (US)
You can cure it with the addition of heat and/or Poly-Vinyl Alcohol. You can find the latter at any shop that carries fiberglass supplies. You spray or spritz it onto the patch.
posted 06-17-2002 05:06 PM ET (US)
I haven't tried that particular brand, but you can get gelcoat patch from Spectrum that works great and is color-matched for Whalers by year and model. It's a little pricey with the shipping, but you'll get great results.
Tip: Don't mix it all at once because the working time is pretty short.
posted 06-18-2002 05:34 PM ET (US)
posted 06-18-2002 06:25 PM ET (US)
PVA is not a hardener, per se.
Gelcoat resin is hardening in the can, but the reaction rate is pretty slow. When you apply it, you mix it with a catalyst that increases the reaction rate.
Heat also increases the reaction rate.
Assuming you added enough catalyst to get the reaction started, the gelcoat is going to harden.
Air seems to suppress the curing, so to exclude air a layer of PVA is often used. PVA also works well as a mold release, too.
I do not believe the PVA enters chemically into the reaction, but it enhances the hardness of the cured resin by helping to exclude the air.
posted 06-18-2002 08:48 PM ET (US)
My understanding of PVA matches yours; it blocks air and speeds hardening. I have also had good luck with the Spectrum patch putty and have never had to use PVA with it.
posted 06-19-2002 10:25 AM ET (US)
Spectrum patch paste has a type of wax mixed right in with it that negates any need for a curing barrier of any sort. Gelcoat that is not patch paste (does not have the added wax) needs a barrier from the air in order to cure.
PVA acts as has been described; it does not chemically interact with the curing gelcoat, but provides a temporary barrier that is water-soluble and can be washed away when the gelcoat has cured. Wax paper, and other things can do the same thing under some circumstances, but usually not as conveniently as PVA and usually not without marring the uncured gelcoat when it is applied...
I'm trying to think of the chemical that is used as a catalyst for gelcoat, but I'm drawing a blank...(it's not PVA)...
posted 06-19-2002 12:42 PM ET (US)
The product I'm talking about here is Sea-Fit Gelcoat patch. It is widely sold, comes in a small tube, ready to apply. There is no mixing of hardener with this stuff. Dab, and be done is what the instructions say.
I can't believe one could get a better airtight seal with wax paper than I got with scotch tape, unless the presence of wax is what is going to cause this stuff to cure.
I guess my next stupid question is where do I get the PVA?
posted 06-19-2002 03:15 PM ET (US)
I have never worked with the Sea-Fit gelcoat patch that you have, but I would have to wonder about two things: first, I would wonder if there weren't some obscure instructions somewhere that weren't obvious to you that make reference to some kind of catalyst, simply because in my limited experience I have never seen or read about any kind of gelcoat that didn't need some sort of catalyst to cure, whether in the presence of air or not. Could simply be a new one on me...Secondly, I would wonder about the chemical make up of the adhesive in the scotch tape, and whether that could have a negative effect on the curing if in fact your gelcoat does not need a catalyst.
The last I knew, Evercoat was selling PVA in the Gelcoat section of the West Marine catalog for about $7.00 for an 8 oz. plastic bottle.
The first thing I would do is get a bottle and try some on a new Sea-Fit patch, and see if it helps (can't hurt).
I take back what I said earlier about the possibility of obscure directions - I just opened up my 2001 West Marine master catalog and there on page 423, just above Spectrum Patch Paste kits and Evercoat PVA, is your Sea-Fit one-part, no-catalyst Gelcoat patch. Search me...If the PVA doesn't do the trick on the Sea-Fit stuff, I'd forget that and go for some spectrum patch paste. There are a number of us here who have used it successfully.
posted 06-21-2002 02:17 AM ET (US)
Kingfish, the hardener/catalyst is MEKP, methyal ethyl keytone peroxide. Joe
posted 06-21-2002 10:17 AM ET (US)
MEKP - That's it!
Thanks, Joe - these senior moments seem to be getting closer together...
posted 06-28-2002 02:38 AM ET (US)
MEK Peroxide will work if you just spray it over the finished repair. Typically you want it mixed into the gelcoat. All it is intended to do is "kick" the gelcoat. If the repair is done but not kicked, use a hair dryer. All that cures gelcoat is heat. BUT.. not too much or too close it will bubble and fail. Once the heat has been applied for a minute or two, at a distance of say 6-8"...walk away.
The wax is Styrene and is used generally when spraying gelcoat although I usually use it to thin any gelcoat. PVA is mold release and can be sprayed on a finished repair to assist in bringing the waxes to the surface. It will not cause gelcoat to cure. PVA gives a smoother and shinier appearance and doesn't let the gelcoat exotherm too quickly. FYI
posted 06-28-2002 10:31 AM ET (US)
Thank you for the additiponal background.
With all due respect though, my experience has been that PVA does create a barrier from the air which action in fact does promote curing, and gelcoat that does not have a barrier of some sort (i.e., PVA, wax paper, a mold surface, etc.) does not cure, or at least cures so slowly as to be problematic short of the introduction of heat.
Further, the PVA I bought was sold to me for the express purpose to provide such a barrier. I used no styrene and thinned the gelcoat for spraying with acetone.
I think I am reading your post to indicate that there is no barrier from the air necessary at all and that gelcoat will cure just as fast with no barrier as it will with one. If that is what you are saying, I am confused, and would wonder if you are referring to gelcoat that has had styrene introduced into it.
posted 06-28-2002 10:37 AM ET (US)
I use just a generous and multiple application of spray wax (household, automotive - anything) and give it a little time. The main thing is to block the gel-coat or other fiberglas material from the air.
Incidently guys, be a tad careful with the MEK - which is one of the best solvents known. I will never forget unpacking from a move from Pittsburgh to Idaho - when I found Mayflower had placed two bags of fertilizer on the bottom of a garage box and a gallon of MEK above that. Had the can of MEK leaked or had been ruptured, the hole would have been big! ----- Jerry/Idaho
posted 06-28-2002 10:42 AM ET (US)
Newboater - I was wondering if you had an update on this? I looked at a tube of the stuff in Westmarine and it says that it's removable up to 8 days with acetone. Maybe it's just really slow curing. Did it finally harden on its own?
posted 06-28-2002 12:31 PM ET (US)
Kingfish - I agree.
You used the most appropriate language. I wasn't clear. PVA does "promote" curing. It is not required but certainly useful in protecting the gelcoat from air. PVA by itself doesn't initiate curing as a chemical reaction. PVA restricts outgassing which increases the normal un-catalyzed curing that is already occuring in the product. Hell, I'm confusing myself:-)
Acetone as a thinner will work but eventually damages the structure of the polyester when used in quantity. It is too aromatic to stay in the repair long enough and the polyester will become less elastic than with the use of styrene wax - particularly when spraying. Another partial reason is due to the high solids content of the colorant. It would probably be better used on clear gelcoat.
I stand corrected.
posted 06-28-2002 01:10 PM ET (US)
I've checked the spots I used the Sea Fit Gelcoat Patch on a few days ago and I could still put a dent in it with my fingernail. I haven't tried heat or PVA yet. I try to only go to West Marine once or twice a month.
I'll update after I take a closer look this weekend.
posted 06-28-2002 01:16 PM ET (US)
I appreciate your input and the clarification - I just learned something here, and the next time I fiddle with gelcoat, I will have my hands on some styrene.
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