As I was going over a number of resin options for my next board something hit me: how important really is the resin’s tensile strength? Shouldn’t you let the fabric handle the majority of the load? That would leave me thinking that the best resin to use is the resin with the highest elongation % (which from my findings would be the System Three epoxy coming in at 11%).
I’m going to give a plug to Resin Research resin. I wasn’t quite sure which resin I was going to use until I talked with Greg Loehr today. I phoned up with a few resin questions and he was extremely helpful. He spent 20 minutes answering questions that I had. I hung up being extremely impressed with his knowledge and his desire to innovate. I appreciated being treated as a valued customer even though I haven’t ordered yet and when I do it will only be 1.5 gallons. I’d recommend checking it out.
i, too, have had a couple chats with greg about this stuff. resin flex is important, but if it’s too flexy, it’ll shift more of that stress to the glass. your lam/hot/gloss coats should all be working together to make a strong board. i just recently started with RR epoxy, and have been most impressed thus far. it’s definitely my epoxy of choice (although i’ve never used system 3 myself…i’ve heard things that lead me to believe RR is far superior for surfboard building purposes…and additive f is miraculous).
As I recall, while it is true that System Three has slightly better tensile and modulus strengths than RR (according to the technical data sheets), I believe the limiting factor in this regards is the fiberglass cloth (you should be using S cloth with epoxy), not the resin.
I have used System Three for the last year. I am generally happy with it, but then I have no other epoxy to compare it to, only polyester resin.
I am on the last of a 1.5 gallon kit I ordered at the end of last summer. When that is gone I plan on trying some RR epoxy. From what I have read and heard it is every bit as good as System Three and it is definitely cheaper. I paid $127 for my 1.5 gal kit from System Three, whereas as a RR 1.5 gal kit is only something like $95!
P.S. System Three has a nice website with an email and/or a 800 phone number you can call for info. They have been quick to respond to my questions.
Well it looks like I’m in the dark then on what really matters in a resin if RR epoxy is comparable to sys 3 epoxy for surfboard use. RR epoxy only has an elongation % of 2.3 (1/5th that of sys 3). In further comparison though, RR epoxy does have a tensile strength ~1.5x that of sys 3’s resin as well as a compressive strength ~ 1.3x sys 3’s.
I really couldn’t tell you which is better, System Three or RR, or why! It seems like it may be six of this, half a dozen of the other…
On the other hand, supposing that they are basically comparable to each other, and that either should do the trick, RR is considerably cheaper and supposedly safer to work with than System Three, according to Greg Loehr RR is not as much of a sensitizer as is System Three (although I personally haven’t had any problems in this regard, I try to work as safely as I possibly can).
Like I said previously, I plan to at least give RR a try next time around, and then perhaps I can make a better comparison between the two.
I loved the Resin Research Resin but it was expensive for me. It was $150 for a 1.5 gallon kit. I was able to buy the System 3 resin for $110 /1.5 gallon kit. The system 3 was a yellow color whereas the RR was completly clear. Anyone know where to buy Resin Research Resin in Houston, Tx for any cheaper? That’s what I’d buy if I could find it for cheaper.
The best epoxies will always be hazier than the ones made specifically for surfboards. Yet another trade-off between function and fashion. If you’re spending the money to go the composite route, seems like an easy decision.
This site has probably already been posted about, but I’ve found it very helpful so here it is again - http://www.netcomposites.com/education.asp . It has loads of good advice with the techs to back it.
They will ship it to you for only $91 total cost (no middleman). Check out their website http://www.resinresearch.net
“The best epoxies will always be hazier than the ones made specifically for surfboards.” - Losos
I seriously doubt that the quality of an epoxy resin can be judged on whether or not it is clear.
I know System Three has some beautiful clear epoxies used for boats and furniture which are useless for surfboards because they yellow when exposed to sunlight. It would be necessary to add expenisve UV inhibitors and then you would be mucking about with the formula and perhaps weakening the strength of the expoxy.
Surfboard epoxies, on the other hand, are formulated from the gitgo with UV resistance in mind. Part of the reason surfboard epoxy is more expensive than many other epoxies is due to added UV inhibitors.
$150 for 1.5 gallons? I charge $106 delivered. If you buy more you can get discounts. Who you buying from?
Losos,
If you want elongation try RR 2020 or 2040. They have much more. Surfboards should generally have elongation of about 2-3%. More than that gives the surfboard a spongy feel. Kayaks go 6%+ which is for impact strength. Boats usually go about 4-5% because they use a structural sandwich. If your sandwiching boards much of the stiffness is in the composite and you can then use a more flexible resin (2020 at around 4%) in that application. But generally you want to go for more stiffness to protect the very light foams we generally use and the stiffer resins give a crisper feel. Also, going by published numbers never serve as very good proof of a resin system. The only true way to tell whether a resin is good or not for a particular application is to test yourself in your application. This we’ve done for over 20 years. We produce what is generally needed for surfboard construction. Also, clarity has nothing to do with strength. Clarity has to do with purity which we do better than anyone.
Interesting discussion but I hope someone can clarify something about elastic deformation (elongation). It is stated at the below website that resin should not be doing most of the work when it comes to strength…
http://www.djaerotech.com/dj_askjd/
if your cloth has an elongation of 3% then the resin should be slightly higher, say 4%. What isnt discussed is the resin’s effect on stiffness and compression failure…and how does cloth drapping before lamminating affect stretch…meaning that one can lay a cloth with or without some tension…does it affect the lam’s elongation performance?
Also, I noticed when I add some petro-based dyes, perhaps too much, to RR epoxy it seems to affect stiffness…havent proven this just a one time observation. How much filler can be added to epoxy before it suffers ill affects?
Greg said,
If your sandwiching boards much of the stiffness is in the composite and you can then use a more flexible resin (2020 at around 4%) in that application.
greg, would you reccomend your 2020 for those of us dabbling in balsa a la bert? I have a board’s worth of your regular 2000, perhaps I’ll use that on my first one, but should I go for the 2020 or 2040 next time? also, what about 2040 next to the foam to match it’s resiliency and 2020 on the outer shell to give more stiffness? other combos?
Thanks, wells
Elongation is only one factor, stiffness is another. There are fabrics out there that have superior elongation and yet are quite stiff. IMHO if your using something like S-Glass, that fits that type of perameter, then you use the resin that gioves you the finished product that your aiming at. If the board is for entry level surfing then you can give it more impact strength (ding resisance) and use 2020 or even 2040. High performance requires light weights which calls for very stiff resin. As I said above, when doing a sandwich you have more stiffness built in which may allow you to use a more flexible resin. But if you were making a very thin board you may want to keep the stiffness in. There’s no right of wrong here, just depends on what your target is.
I bought one a one gallon kit from Craig Chafin for $100. I just made it the $150/1.5 gallon kit to show a equal amount of resin comparison. Where can I order from? A website or directly through you? I don’t need any right now but I’m sure I will soon!
this guy is so far ahead , hes even engineered the resin to have superior performance and strength as well …
if i had my way and was using the resin down here in oz , i wouldnt want anyone else to use it …
greg has set the stuff up so just using the resin will improve your boards performance , just through better cross linking adding to quicker energy transfer …
dont have time now , but it would be nice to have a discussion about the different aspects of the data sheet and how they relate to performance differences in different resins …
i said it somewhere else , you should just make insane light strong high performance boards , and show all the so called industry leaders whose really got the ball …
i would love to get the stuff in oz , how much needs to be transported before it becomes viable …??
regards
BERT
Quote:
it would be nice to have a discussion about the different aspects of the data sheet and how they relate to performance differences in different resins
This would make a huge difference to me. When I look at the data it is almost impossible for me to tell what is important and what isn’t.
This isn’t as technical as the rest of this thread but I’m gonna put in a plug as to the clarity and yellowing resistance of RR epoxy. As an experiment, I’ve had a board sitting out in the sun for 6 months and it’s yellowed only slightly. A HUGE improvement over past epoxies that typically yellowed badly with slight UV exposure.