Has anyone out there used epoxy on standard pu blanks? If so, did you get any interesting results, good or bad?
yea …
they yellow off a little quicker and have a yellow tinge from new (depends on which system as well),tend to pressure ding easier but no stress cracks or fractures …
you can get an epoxy glass job a little lighter so i like to use a harder foam to help with pressure dings and the weight is almost offset by the weight of the glass job…
the result is way more durable conventional style board…
i wonder if pigment would help with yellowness???might try on the next one…
regards
BERT
http://groups.msn.com/thegrasshoppersurfboard/shoebox.msnw?action=ShowPhoto&PhotoID=42
I made this board w/ a Clark blank and ResinResearch 2000 Epoxy w/ fast hardener and AdditiveF
Loved the epoxy - tougher and gives the board a more solid feel. Easy to work with and no styrene fumes! With Add.F, you can sand any stage along the process without gumming up the sandpaper. The resin flows and saturates easier so you can you much less resin making the board significantly lighter.
Epoxy minuses:
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Very temperature dependant so if it gets cool, it can take a long time to cure, and you cannot speed up the process by adding more catalyst, you have to use heat.
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You have to mix very EXACT so that makes it harder to mix small batches (along with the long set time - i always want my small batches to go off fast to get to the next step) or multiple batches for resin swirls.
Those minuses are easy enough to work around. It takes a bit more patience and attention but the end product turns out better. I really like the epoxy. My board turned out very light and it is tougher than a poly lamination but it feels a bit stiffer also (not in a bad way). I want to try the more flexible resin the 2020 to see how that rides.
the Resin Research epoxy seems to be clearer than simlar making a whiter board… i guess a lot does depend on which system you use.
perfect looking board for 170 in grovel and small stuff???..
i use different resins for different applications …5 minute for plugs and vent plugs and bang ten for fin set ups …all still epoxy but hardens at different rates plus my main resin has 5 hardeners from 18 minute pot life to 270 minutes …theres five all together with the same mix ratio . so if you want you can mix and match…for example if i only had the two hardeners (18 and 270) if i mixed them together id get 145 pot life…
so you can get anything that suits you or the size of your job …
regards
BERT
170 lbs? close im 155 and its very bouyant for me.
170 cms? close again. actually 5’9 (175 cm)
definately good for planing instead of bogging in the slop.
bert you have it wired for epoxy boardbuilding…i would love to see one of your boards in person and also a cross section of how everything comes together…
yea eventually i will get an act and get some device for photos then i will start posting some interesting stuff…
regards
BERT
Epoxy on urethane works great. Much easier to laminate with and makes a much tougher board than polyester. It is lighter as well but denting is somewhat worse when using the same blank and cloth. As Bert said above, using the next weight blank up (a green in place of a blue for instance) solves the denting issue, the board then comes out the same weight and is MUCH stronger. Our resins have better clarity than polyesters and yellowing is at a slower rate than poly. As for speeds we have three from 25 minute to 200. There are techniques we have developed over the years to eliminate the small batches and speed the process mostly by doing multiple jobs at once. All the hardeners are 2 to 1 so you can also mix and match for different applications. There are also three resins with differing flex patterns so you can build boards with differing flex charateristics. Polyesters don’t offer this. You can use any type of foam, not just urethane and polystyrene which gives the builder a lot of versitility, right Bert? Any other questions you can e-mail me direct at .
Thanks for the info everyone. I’ve made many polyesther boards, and have worked with epoxy for many years in a different industry, just never had the chance to put the two together. I had a feeling it would open up the variables, and with no quality sacrifice. Thanks.
im starting to drool …how the hell we gonna get this stuff into oz???
stuff it …thats one of my next jobs …find out about getting it here myself…
greg while were on epoxy…whats your thoughts on postcuring? does your resin respond well to postcuring…?
in my last factory we had a huge oven which could take 6 boards while under vacumn…we could layup and vacy a board throw it in the oven and be working it 2 hours later it enabled us to run up to 24 vac jobs a day…
anyway ive moved now still have the same pump with 6 outlets but didnt worry about an oven set up coz i just leave em overnight, couldnt see myself doing more than 6 a day…
but now that a little time has elapsed , im claiming that the baked ones were way harder and crispier,im actually gonna set up another vac oven ,not for increased production but for quality …
and over the years using different systems ,some responded unbelievable to post curing ,to the point where the strength was increased far beyond what you could get with a normal room cure…
regards
BERT
Bert, I worked in the aeronautical industry for several years, lot’s of prototype and moulding work, all epoxy, some p/e gelcoats (better range of colours (cammo… I didn’t say that!!!).
Where possible we vacuumed, 12-24 hour workshop temp cure 25-26C, then trimmed etc and baked. We had a large fan circulating convection oven, not pressurised, and a recommended baking cycle which lasted about 30 hours. 40C for 6hours, then 1 hour increase to 60C for 6 hours, again to 80C for eight hours, then 8 hours of gradual cooling. At the end of the cycle it was still around 30C.
The baking process increased the strength characteristics by a huge margin, sorry I have no figures. Definitely worth it.
I’d get or build yourself another oven but don’t waste money on a pressurised one. As I understand it, a pressurised oven is only essential for pre-pregs which need it for the actual curing process.
initially we baked to speed up the process so we could get 4 vacys a day off one vac outlet instead of one a day at room temperature …they actually got vaced and baked simultaneously you could actually see the resin boiling …i reckon some of the resin must have vaporised coz the baked ones always seemed lighter …
we would turn the oven off at night and let the last ones room cure overnight ,then do 3 runs of baked ones throughout the day …
the room cured ones were always heavier and softer…
stupid thing is i actually never did a test to verify that one…
so much for keeping records and doing tests , maybe it just seemed obvious so there was no need to test the degree of difference…
regards
BERT
ps wildy where are you now???
gettin waves somewhere??
or doin something else?
Bert, I’m in Colorado and here is a picture of the only waves I’ve seen in a while! Doing some snowboarding and snow kiteboarding among other things. For the last few years I’ve been away from the surf more often than near, but, as you can probably tell, I’m still hooked, and still want to see surfing and surfboards progress. You, Greg L and a few others seem to be the only ones forging ahead. Good onya mate!!! (Sorry everyone, but I’m still an Aussie!)
Quote:
…i reckon some of the resin must have vaporised coz the baked ones always seemed lighter …
Bert, I’ve worked with vaccume bagging and autoclaves in the boat building industry. I’m pretty sure that if you’re baking and vacuming simeltaneously, the epoxy becomes more viscus initially and flows out better in your laminate. Hence, less resin remains in the laminate resulting in a tighter & lighter matrix.
Our resins were developed for room temperature cure. Post curing will give avantages to any thermoset resin and ours is no different. The cure schedule posted by Wildly above is excellent but with boards it’s doubtful you could go to 80¼C. In fact 60¼ is pushing it. Toms comment is especially true if your using bleeders.
We are working right now with a fabric company in LA on new cloth that will allow better glass to resin ratios still using hand layup. Laminating techniques will be different, (we use extremely stiff sqeegees) but the cloth doesn’t get air in the weave, like the boat fabrics we use now. The 6 oz we have is all singles yarn and it finishes at the same weight as 4 oz. We also have a12 oz. a 9 oz. a 4.5 and a 3 oz. in the works. Ideally, you laminate one layer per side using the correct fabric weight for your finished laminate. The surface is very smooth (smoother than regular 4 oz.) so hot coats are very clean and sanding doesn’t mar the cloth.
Nice Greg, let us know when that cloth will be ready for prime time and how we can get it.
yea tom you are correct there if like greg said your using bleeders and sucking out the excess ,we basically were running closed systems ,which means all the resin put in the job stayed in the job …if you boil water it gives off vapour and reduces…
what happens when you boil resin???coz i seen it boiling i naturally concluded it must be vaporising and turning to gas…not forgeting as well that you are lowering the vapour pressure by using a vacumn…if the atmospheric pressure is low enough water will boil at room temperature…so imagine negative pressure plus adding heat,
now after all that maybe greg can answer the question ,what is left if you boil resin ? would it be a more concentrated resin being stronger?? or would you boil off some good stuff as well…??
what elements are involved and what bonds are being broken??
regards
BERT
Hey Bert, I hope you’re asking Greg L, because I’m no chemist and haven’t got a clue. I have had to quick cure a few urgent plane parts at times, so we were instructed by our expert to heat to boiling, and as far as I know there was no detremental effect. Greg.
Now we’re getting out of my area of expertise. But, if you’re working in a closed system:
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How do you create a vacuum without evacuating gases and to some degree liquids.
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If you raise the temperature and lower the pressure, H2O turns to gas and then recondences on the walls of the system and you don’t lose any mass. It just changes states.
We know that as epoxies are mixed they create an endothermic reaction and gives off gases. But, these gases are not like water vapors where the entire molecule just changes states. They are weaker linked molecules escaping the chemical bonds that entrapped them at lower temperatures. Some of those gases are essential to create a cured matrix. But, some of them can also aid to the elasticity of the cured matrix. So, over cooked epoxies can and do become brittle. So, the answer to your question is highly resin and atmosphere dependent.
Tom is exactly right. Generally what you will loose by boiling are the parts of the formulation that control flexibility (modulus). Beyond saying that, well, Tom said it all.