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EPOXY

Epoxy is, in most ways, superior to polyester.  If you want a durable and/or light board, try epoxy and "S" cloth.   For surfers who refuse to use more cloth than what is used on production boards, it is worth the extra cost.  Together they will increase the cost of your materials approximately 20%-30%.  Epoxy will work with polyurethane or polystyrene foam, and with "E" cloth.  Using epoxy and "S" cloth in place of the usual polyester "E" cloth (especially on thrusters) is an easy solution to the disposable board problem.  As oil prices, and board prices continue to rise, so will the desire for a durable board.

If two palm size disks, one polyester and one epoxy, are dropped from chest height flat onto concrete;  the polyester will shatter and the epoxy will be whole.  If a polyester "E" cloth board hits an epoxy "S" cloth board;  the polyester "E" cloth board will be fractured, while it will be hard to find the area of impact on the epoxy "S" cloth board.  This is because "S" cloth is stronger than "E" cloth, and epoxy is stronger and more elastic than polyester.

Although, in today's market of disposable boards, it would be preferable to have a stronger board instead of a lighter board, you could save around 2 lb. by using epoxy and "S" cloth.  It is more damage resistant than polyester and 'E' cloth so you could use lighter cloth, or a lighter blank such as  polystyrene foam, and/or a stringerless blank ).

For the ultimate in lightness and strength try epoxy on carbon fiber.  My friends and I have done a number of boards with 4.8oz.carbon ( www.fiberglasssupply.com  ) on the top and bottom with a 4.8oz.carbon fiber deck patch over stringerless extruded polystyrene foam (no suitable carbon cloth is available in 2008, due to the war).  It is pigmented white to keep down the heat (carbon fiber is black)  The gloss coat takes a lot of extra work with carbon and adds weight.  In fact, a carbon board with a solid white gloss coat will be almost identical in weight to an "S" cloth board with almost twice the cloth weight, with no gloss coat.  It is questionable if carbon is worth the trouble.  I now believe it is most practical in a cool climate, where a white gloss coat would not be needed (See GLOSS COAT).  If you want a pretty, clear board use the "S" or "E" cloth. 

After trying over ten different epoxies, as of 2012, a number of us of us have switched to www.uscomposites.com for epoxy and other supplies - cloth and epoxy is generally cheaper.  After trying all the uscomposites epoxies,  the Klear Kote epoxy is the best buy. Although very thick, it works well for all surfboard building. It has good u.v. protection and is the clearest of all epoxies I have used. The two gallon kit - one gallon of epoxy and one gallon of hardener costs less than the one and a half gallons kit of surfsource or resin reseach resin. The extra resin is good to practice with, and alows the smart first time glasser to have more than the minimum amount of resin available for each coat.
Also excellent is the ss2000 at www.surfsource.net - a very fast, and efficient company.  ss2000 is as clear as polyester, and has good u.v. protection
Many shops are now using the very good rr2000 epoxy from Resin Research.  If you use this epoxy, disregard the amounts of resin that you may have read numerous builders claim is adequate.  First time builders will find it very difficult to reproduce the results of these experienced glassers.  If you want a  finish that stays clear (epoxy discolors slightly over years of sun exposure) it would be safer to coat the epoxy with a u.v. blocker such as polyester resin.  I like 100% epoxy (no pigment, solvent, thinner, or additive). 

Showroom boards that say epoxy on them are usually only epoxy in the laminate (cloth).  The hot coat and gloss coat is often polyester (usually polyurethane gloss coat on Surftechs).  Using a polyester gloss coat over an epoxy lamination will probably not save any money for one board due to the high cost of small units of resin.  Keep it simple on your first board;  use all polyester or all epoxy. 

Pay close attention to the epoxy mixing percentages.  If you miss the percentage by more than 5% it won't harden reliably and will be weak.  Mix it for about 3 minutes, being careful to mix any resin sticking to the container sides and bottom.  Thorough mixing is critical to good strength and hardening.

Pay even closer attention to the temperature.  If the specifications say that the epoxy will set up in 30 minutes (pot life), that usually means at 78 degrees.  With every 10 degrees of temperature change the pot life will be doubled or halved respectively.  If it's close to 80 degrees, put it in the refrigerator before using.  Do not start an epoxy lamination at over 80 degrees (starting at 80 degrees, in the morning, with the temperature rising is ok).  At 100 degrees, epoxy can catch fire (it happened to me)!

Sand in between coats and wipe with alcohol for good bond when putting polyester over epoxy (not recommended on your first board).  If re-coating epoxy with more epoxy, do not sand between coats if it is applied within twenty four hours.  "Fish eyes" are a common bubble-like imperfection (dry spot) in an epoxy hot coat.  "Fish eyes" are less common in cooler weather, and can be reduced on hot days by keeping a fan or fans blowing on the wet surface as it gels.  If you do this, turn on the fan or fans before mixing the resin so any dust will be blown away first.  If you still have fish eyes in your finishing coat, drip some resin in the fish eyes, over filling the area slightly.  If desired, sand the excess and finish (See GLOSS COAT).  Some builders claim that epoxy can not be made to produce a perfect, shinny, gloss coat as can be done with polyester.  It can.  It simply takes twice as much work to sand and buff it (use 100 grit at start).  Some builders find an epoxy gloss coat with no sanding or buffing acceptable.  Gloss coats are not necessary.

Note that epoxy has the desirable characteristic of going from slightly gelled to hard at a more gradual rate than polyester.  This makes it less likely the builder will be caught in the middle of a procedure with resin hardening so fast he can not finish.

Consider the possibility that epoxy is, in most ways, superior to polyester.  Try it.

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