I used RR epoxy to glass a Clark blank. Can I use regular poly lam resin to set the finbox? Do you think I will have problems with the subsequent epoxy gloss coat that I plan to use? The main reason for wanting to use the poly resin is the fast setup time.
Thanks,
Rick
in that scenario, there wouldn’t be any issues with the epoxy glosscoat…go for it.
Hey RandR,
Don’t! I repeat, don’t take short cuts by mixing epoxy and polyester. The results of asking the to materials to marry with each other is always a failure. Some failures take longer than others of course. I speak from experience. If you want to find out the hard way go for it. they just don’t bond to each other very well at all and as a result the slightest stress will result in a divorce which is always painful.
Mahalo, Rich
epoxy will bond to poly…poly won’t bond to epoxy. in this case, poly bonds to foam when he sets the finbox, and then epoxy goes over it with the glosscoat…so what’s the problem??
Hey Soulstice,
If poly will bond to epoxy how come a whole bunch of Joey Thomas’s twinzers with poly hot coats on them delamed after two session. If epoxy will bond to poly how come my beautiful 9’5" Junod with a cloth inlay in poly with two layers of epoxy 6oz over it is delaming where two materials come together. Joey trashed all of his boards and you can bet I won’t try and save the cloth inlay with another epoxy lamination. It’s all comming off over the inlay. and Ploy is going over it. Just hope I get the router set shallow enough to get it all off nice and clean. It’s sad cause the rest of the board doesn’t have one ding after dozens of sessions.
Proof’s in the puddin’ ~ It may work for someone else but I’ll never go there again.
No Worries, Rich
first of all, poly will NOT bond to epoxy (didn’t i say that??). epoxy, however, will bond to poly…but i think any chemical bond of epoxy to poly needs to happen before the poly is fully cured…otherwise, it’s just a mechanical bond…which is probably why your epoxy over poly board is delaminating (probably wasn’t scratched up enough for a decent mechanical bond).
Soulstice!!
I’m very interested about some pics of any delamination between epoxy and polyester.
I’m building an EPS longboard, which I’ve sealed with epoxy and one 4oz fibreglass layer, quite dry to allow a good mechanical bond with the poly I’m planning to use with full cloth inlay and final fibreglass layer.
I made tests on EPS scraps and they seemed to work OK, but couldn’t test them on flex. I guess I should sand down the EPS blocks of the tests and try to flex them.
I agree, with a caveat.
It’s a rule of thumb.
That means that someone always gets beat.
Polyester bonds to polyester.
Epoxy bonds to epoxy.
Epoxy bonds to polyester.
Polyester DOES NOT bond to epoxy.
But here is the best part…
Nothing bonds to polyester like polyester
and
nothing bonds to epoxy like epoxy.
If making the effort why plan to fail?
Yes, polyester has been used in the past as a hot coat over epoxy, but in most cases it eventually delams. I’ve heard this from a FL shaper who worked where they did it. Why would anyone want epoxy over polyester? Strong over weak. Building a weak link into the chain eventually means problems. (I have found that in any system of any kind looking for the weak link is exactly where you will find the source of the failure.) There are too many intercoat adhesion issues at this stage of the game to advise putting the two together.
Since polyester is slowly being phased out, currently the majority of research is being conducted in bettering epoxy formulations. Poly research is primairily confined to finding ways to make it EPA compliant. Other factors take second place. Rather than looking for ways to make polyester stick to epoxy, research is being done to find ways to make epoxy stronger, faster, and glossier. It’s easy to see the future when you know where to look.
Thanks for the input guys. This board has turned out pretty good so far so I guess I am not too willing to experiment and risk delam issues down the road. My primary reason for wanting to use the poly for the finbox is that it has a faster setup time. My previous experience with epoxy and setting the finbox didn’t go so well.