Epoxy & Clark: Why Not?

Given that Epoxy has better strength and adhesion qualities, it seems like a better resin than Polyester. But, instead of using Polystyrene blanks with epoxy, that are hard to shape and have water retention problems, why not use Clark polyurathene instead. Granted, it may be slightly heavier, it will not make that much of a weight difference in smaller boards. Any one useing Epoxy and Polyurathene blanks? What is your experinace? Shine

I’ve used epoxy on styro, but not on polyurethane foam. From several sources, epoxy works on polyurethane foam. And yes, in my opinion epoxy lams are much stronger than polyester lams. There are two main drawbacks to epoxy. I’ve sensitized myself to liquid epoxy, so every time i touch it I break out really bad, very common among epoxy glassers. The other drawback is price. UV inhibited colorless epoxy resin costs about 3 times as much as polyester surfboard resin. That said, there’s a compromise, vinylester resin. Vinylester resin costs only 10% to 20% more than polyester resin, but it’s strength and bonding are about the same as epoxy resin. Another vinylester positive, according to accounts here, you can use Suncure UVC 2000 UV catalyst to cure vinylester within minutes. The drawback to vinylester resin is color and clarity. I’ve never used vinylester, but suppliers say it has a brownish tint. If you use vinylester resin, you’ll probably want a pigment coat.>>> Given that Epoxy has better strength and adhesion qualities, it seems like > a better resin than Polyester. But, instead of using Polystyrene blanks > with epoxy, that are hard to shape and have water retention problems, why > not use Clark polyurathene instead. Granted, it may be slightly heavier, > it will not make that much of a weight difference in smaller boards. Any > one useing Epoxy and Polyurathene blanks? What is your experinace?>>> Shine

POLY/RESIN is the best, it is a true chemical bond. EPOXY IS NOT !!!That’s why there are so many delams popping up in local dingshops.Herb

Builders in the NW have been doing it for years, mostly with sailboards. It is the same process as a surfboard. The Clark Foam / Epoxy boards are using the clear SB-112 epoxy. Vinylester is another alternative, but you have to paint it because it is not UV resistant as SB-112 is.>>> Given that Epoxy has better strength and adhesion qualities, it seems like > a better resin than Polyester. But, instead of using Polystyrene blanks > with epoxy, that are hard to shape and have water retention problems, why > not use Clark polyurathene instead. Granted, it may be slightly heavier, > it will not make that much of a weight difference in smaller boards. Any > one useing Epoxy and Polyurathene blanks? What is your experinace?>>> Shine http://www.viser.net/~anthwind/

POLY/RESIN is the best, it is a true chemical bond. EPOXY IS NOT > !!!That’s why there are so many delams popping up in local > dingshops.Herb I have had NO epoxy delams in 4 boards. Sure would like to see some first hand testimony of this.

Given that Epoxy has better strength and adhesion qualities, it seems like > a better resin than Polyester. But, instead of using Polystyrene blanks > with epoxy, that are hard to shape and have water retention problems, why > not use Clark polyurathene instead. Granted, it may be slightly heavier, > it will not make that much of a weight difference in smaller boards. Any > one useing Epoxy and Polyurathene blanks? What is your experinace?>>> Shine My most recent was a super blue blank w/epoxy resin - glass top:3@4oz…Bottom:2@4oz…Good way to go(I’ll not use blue blanks again…Too soft for me…) http://http://216.15.61.234/swaylocks/boards/db.cgi?db=default&uid=default&Validated=Yes&Category=other&view_records=1

I have had NO epoxy delams in 4 boards. Sure would like to see some first > hand testimony of this. …I visit/advise a large volume ding shop here in North O.C. on a reagular basis(Surfixx).I have seen literally 100’s of epoxy lam boards repaired there and the number one problem is delam (some really ugly stuff too!)this problem ranges from the “little guy” builder to the "big time"builders.ALSO I have used epoxy in lots of different building projects (bedding gun stocks,rapping fishing rods,high speed skateboards,to name a few)some with great outcomes… others not so good.I don’t like what I see with epoxy surfboards.Herb.

Obviously I don’t have that much experience seeing epoxy boards come back, but I’ve hung and received training from the local Houston styro/epoxy board builder. I got some pretty good instruction from him, as well as good feedback. As a supplier told me, epoxy will stick well to almost anything, but other things have trouble sticking to epoxy. Epoxy lamination takes a little different set of skills from poly laminating. With both resins, dry surfaces about to receive epoxy must be sanded. However, a hard epoxy surface has to be sanded thoroughly before receiving any kind of resin. Styro blanks are usually used with epoxy. The styro must be sealed before lam to prevent resin wicking into the foam. After sealing the shop must sand the sealant. If any of the blank’s surface is left unsealed, capillary action will force resin into the board. The action causes pressure which can force delams at a weak spot, or later when the glass is stressed. One of epoxy builders’ biggest enemies is moisture. The styro blank sealant is water based. After application, the shaped board must be thoroughly dried before the epoxy lam job, or the board will delam later. Even excess humidity in the glass fabric can make an epoxy lam job bubble, during curing or much later. Some lighter weight polypropylene blanks aren’t strong enough to hold up the more resillient epoxy lamination. Polypropylene crushes when pressure dinged. If it crushes enough, the epoxy glass can spring back out of the foam depression, causing a delam. In the same situation, styrofoam will spring back with the epoxy fiberglass and stay laminated. When Polypro blanks depress under polyester fiberglass, the fiberglass stresses, depresses, and stays depressed. These relationships are merely trends… more and less. Bottom line for glass combinations: Polypro foam is more crushable and turns to powder more easily. Styrofoam is more springy. Polyester glass is more bendable and more crushable. Epoxy glass is more springy. I wasn’t part of the glass shop discussion below, but its bottom line was that a large portion of glass shops can’t get the easier Polypro/polyester jobs done right. Most glass shops have little experience with properly laminating epoxy boards. With all the hurdles above to get exactly right, it’s no wonder that epoxy screwups are pretty common. For anybody building an epoxy board, get it right.

Using too little glass with epoxy also subjects it to delam. It seems some board builders are turning out super lightweight styro/epoxy boards with one or two layers of glass. Epoxy lams work much better with 3 layers. I use 6oz E, 3 layers on bottom, 3 2/3 layers on top. Some of the better shops use the same layers of 5oz S glass. I suspect cheaping the glass job is another main reason for delaminated epoxy bring-backs. The EPS styro I use is weak at 2 lb / cu ft. With all the glass I put on my boards, they still weigh out a pound or two lighter than equivalent poly/poly boards.

For the info…I see where some people go wrong.Herb

I’ve made a few clark foam epoxy boards and the only problem I’ve had was silver dollar size round glass cracks around pressure dings on the deck. I stopped using this combo because I just like the way a poly resin board feels when I surf it! Not as stiff.

. I > stopped using this combo because I just like the way a poly resin board > feels when I surf it! Not as stiff. I have been wondering about this too. I made a few boards with “S” cloth & Polyester. Boards are really stiff and I notice they do not have much flex. Shine

. I>>> I have been wondering about this too. I made a few boards with > “S” cloth & Polyester. Boards are really stiff and I notice > they do not have much flex…I use the “s” glass for my big experenced surfers, that want a small board.Herb.>>> Shine