Re: Gelcoat over epoxy repairs
It has been posted before, and they are the only ones out there saying it's a good idea.
I have personally talked with them about it, when asked directly they say it may not be the best way to do it.
I have tried a few times to get a bond and have never been satisfied with the results, it didn't just fall off, but it didn't stick all that well either.
I have personally spoken to WS Tech Support as well .. I get the same thing. "It can be done but with methodical prep." You cant just use WS and expect a good gel repair Over it without some complications. Your application of Gel could suggest a problem dependent on what solvent you use in the mix. ( styrene, Acetone, Mekp, Cobalt .. many others ) .. could these be a problem with bonding of the gel ? Its NOT a blank page saying the WS system is not compatible with Pure poly products. .. but you will have to Add Solvents. Now .. are they going to suggest if you use XY or z solvent that it would not affect there product bonding issues with your gelcoat ? I doubt they have the RnD developtment team working on these issues.
In a small repair you can use gel over epoxy .. with larger repairs there should be a Tie coat..
Duratec Might ( and I stress Might ) be a viable option for a tie coat.
The thing with trying to poly over epoxy would be an uncured or impropper cure.
I have seen some bad bonds with poly over poxy .. just does not work right IMP.
YD.
Im sure it was not WS epoxy that was used .. but there has been a complete Failure in the curing of not only poly over epoxy but VE resin over epoxy in some of the repairs that I have tried ( and failed ). It just Did NOT cure !
I dont know why .. Im not a chemist .. but I think it had something to do with the Solvents in the Poly. I will Never use Poly over Poxy for a repair and/or final coat again.
OK, here's the deal. I doubt very seriously that West Systems is gonna flat out lie about a test they've done. There are numerous posts on different forums by different people that say they have made repairs using gelcoat over epoxy that has lasted for years. I do understand that some people have attempted it with poor results, where others have succeded. I also know that epoxy is different than polyester and if you do not prep the surface according to the product used, the results will vary. I also realize that if done incorrectly, that it WILL fail. BUT, if done correctly, it appears that gelcoat CAN be applied over epoxy.
I'm not suggestioning that this is the best method. I prefer to use pigmented epoxy for repairs. "Repairs" is the key word.
Your using Pigmented West System Epoxy for repairs ? Why ? .. Your not priming ? .. just going right from layups or thickened putty to Gel coat for a top finish ?
I don't know why anyone would want to apply gelcoat over an entire surfce of epoxy. That would be putting an inferior product over a superior product!
It Would Fail .. has nothing to do with inferior product or superior product .. its just NOT THAT COMPATIBLE for a larger surface.
Not lying, nobody said they were, only that some test methods and the real world may not yield the same results.
And 'May not' is the key here ... there are not a lot of peeps out there that want to spend/or afford West System Epoxy ( I will add that IMO WS is one of the BEST Epoxy Products out there for Epoxies ) Lets not mix up other systems together with WS.
Just my $4.38 worth ...
YD.
