To all the savvies
In vacuum forming, the ratio is 1gram of glass : 1gram of epoxy (all mixed)
But what is the ratio for the hand lay up?
Anybody knows?
Cheers.
that all depends on how much gets soaked up by the foam. the EPS/Epoxy Primer gives suggested resin amounts for laminating – give it a browse.
Hi Soulstice, what document do you mean by that eps primer?
Thanks
P.S. the 6lbs/sq ft foam will get a 2 layer of microballoon epoxy mix.
Cheers
not that much difference wouter
1 to 1 is possible with a handlayup
but its not that important if its 1 to 1
or 1.3 to 1 etc
more resin means a better seal
better seal means more durable
I was under the impression that 1:1 was the ‘ideal’, the strongest whether hand or vac lay up. And, that if you added more resin (epoxy) that it would just add weigth not strength?
Did I miss read something in the past 4 years of Sways CompSand?
Les
Ratios like 1:1 or 55:45 are great, but try getting a good water seal like that… not to mention cosmetics!
Laying up a laminate at 1:1 is great, as the cloth has a near ideal satuation (no pooling of brittle resin), but then hotcoat/filler coats, spray or gloss finishes etc mean that you’re a long way away from 1:1
At least the resin that is binding the cloth together is optimal, and that counts.
You can go to ultra tight weaves, which is one reason “surfboard” cloths exist, which allow you to get less pinholing with lower resin usage, or flatter weaves that take less to fill when hotcoating
obviously you dont want big gobs of pooled resin
but strength is a non issue in compsand
there strong with 2 oz on the outside
water proofing is however very important when you have a core thats loves a drink
really in a 1 to 1 you have a strong matrix wrt to strength under load
but if your bagging and are flattening out the weave then your impact strength is reduced
also likely to have dry spots and pinholes
and as kit says if you have to fill coat the thing anyway then its not 1 to 1 anymore is it
pipe dream i chased for a year
heres an example
take a 2 meter shortboard with 1 layer of 120 gram
you basically need around 120 gram for a 1 to 1 ratio
its not to hard to wet out the cloth with that much resin if you heat and use a wetout table
or even straight on the board if your good
then you have to dick around with the laps
okay shit ive run out of resin and theres some dry spots
off you go and mix another twenty
oh yeah didnt you seal the board with another 100 grams before you did the lam
so you wouldnt get dry spots
and oh yeah another 100 for the hotcoat
why not just mix up 200 grams and lam it like a normal board until the balsa stops absorbing resin and the cloth is fully wet
pull off the excess and your done
exactly same weight in half the time with a better result cosmetically and most likely a better seal
mind you
my opinion is based on a limited experience and limited space and limited resources
i can see huge potential in some modern composite techniques for mass production
but cant see the point in your back shed
btw thank bammbamm for helping me see the light
My shopkeeper told me the best epoxy/resin ratio you can get with vcuum forming is 30/70.
But maybe thats not possible on surfboards? It is, the less resin the better, but it has to be fully impregnated!
I think you can get better than 50/50 with vacuum forming.
its not that its not possible
its just that it is pointless
over engineering!
in the real world the kinda damage that will effect a thin skin over a soft core
is gunna do the job wether its 1 to1 or whatever
another example
4 oz pupee is gunna ding, depress, snap no matter what your resin ratio is
composite board
sandwhich makes super snap resistant,depression resistant
what can you do to improve a composite
make it more waterproof and more ding resistant cuz snap strength and dents arent an issue
im not 100 percent sure on this theory but
if you have a laminate under vac it flattens out the fibers
reducing the thickness of the laminate and potentially reducing its ding resistance
if you use to low resin content there is a real likely hood of dry lams and pinholing
i do see potential in using vac and RT in board building though
but low resin ratios wouldnt be my primary goal
at the end of the day
cosmetics is still the most important issue to the consumers
they dont want to see the weave and you cant paint over it
I think you’re right about actual thickness being reduced using vacuum, but you are not taking away any of the fabrics characteristics, and the vaccuum is also allowing the atmosphere to push down on the lay-up at so many kilo’s per square centimeter adding strength in a pre-pressured sort of way.
If I could lay up by hand and have that sort of pressure holding my cloth down I’d do it every time.
hey wildy
im really interested in this concept
if you take a bunch of fibers and magnify them
you would be looking at something like rovings
they would have a fair bit of air in them so they would have a cylindrical shape
now if you add resin(and the air) you have a 3 way matrix
its a kinda micro sandwhich
now if you take out the air and replace with resin under normal atmospheric pressure
the fiber rope would still be in is cylindrical shape and maintains its thickness
now if you flatten it out under vac
theres less resin in the matrix but the laminate fiber is now flat like tape
its a thinner micro sandwhich
it would have the similar compressive strength (assuming there is no pooling in the handlayup)
but i believe its resistance to piercing impact would be reduced because its thinner
im not saying its fact that a thinner lam is less ding resistant (just a thoery)
but i do question that its is more so than a handlayup
i agree that the weight would be lighter
but in real world we are talking 100 to 200 grams or so all up
the jury is still out on boards in the 4 pound range
so is it really worth the extra effort
i think the main purpose of bagging and what ever is to fill voids and holes in the core and skin material
not for strength
a better seal!
but im still open though
and ive got some wicked stuff on the backburner
but i do think that some of this stuff that gets thrown around, just makes something that can be simple
seem really complicated
To back up what you’re saying, the engineer I worked with kept insisting there is no strength in resin. It’s job is to glue the fibres together, minimal resin equals best strength to weight.
So we were making these foam filled moulded fins and he kept wanting to reduce resin, but eventually the fins were falling apart under surfing stress, and under some good and well known surfers, which was not good, a couple of times all three fins! The best combination was a certain amount of resin, but not minimal, as the resin did an important job besides glue the fibres together.
Another small, yet important thing he didn’t account for was the sideways stress on a fin during performance surfing. He thought the fin just had to hold foil shape as it just had to hold a straight line.
So although the extra work and effort vaccuuming will produce a lighter and overall stronger board, I can see your point that a certain amount of extra resin skin thickness provides a better day to day impact resistance, and generally easier to manufacture.
I would prefer to go the hog, and if it gets too light under vacuum, add another layer of fabric, that will fix the impact thing too. Yeah it’s extra work, probably not necessary in most cases.
heya wildy
re.
I would prefer to go the hog, and if it gets too light under vacuum, add another layer of fabric, that will fix the impact thing too. Yeah it’s extra work, probably not necessary in most cases.
i guess that another point as well
the extra layer of fabric definitely improves ding resistance
does this in turn increase stiffness somewhat
so there is strength in the resin as it shows from your fin making friend
in gemstones theres toughness and hardness
so while a flat disk of resin is easy to snap (not tough)
its quite hard to poke a nail through when its a certain thickness (hard)
mixed with fiber you have hard and tough
tough stops the board breaking and hard does a good deal to prevent holes
its finding the balance i guess
like i said im not against bagging at all
i think its needs a thoughtful approach however
Did I miss read something in the past 4 years of Sways CompSand?
Les
Not if you paid attention to some of my posts.
I was almost screaming about proper sealing way back,
very few listened. Those jumping thru hoops to reduce 200g of resin content, only to have the board gain 400g after one session. PU and EPS foam and Balsa wood are the worst. Now after lots of trial and error, sealing has appropriately taken center stage.
Its real simple; if surfboard core materials were 100% waterproof, you could easily hand do better than 50/50 volume fraction, cuz you wouldnt need a water tight seal. Ive done better than 50/50 with a simple roller/squeegee method. Thats about 5 parts fiber, 4 parts resin, easy. And simple extra step or two could yield even “better” ratios. Of course, “better” for volume fraction, but not for seal.
Re Wildy’s (consultant?) engineer experiences; I think Kenz said it best; you gotta throw away the aerospace composites manual when it comes to surfboards (ex; cloth has virtually no stiffness; High Modulus resins adds stiffness to cloth).
Marine composites too. Really good well made boats have solid one inch thick fiberglass hull bottoms. Thats the best construction for larger rec boats. Any guess how much that weighs? How much that costs? Maximum profit motivated boat mfgs love sandwich cuz it uses less expensive materials, thus higher profits. Just dont expect that sandwich core hull to last.
Again, throw the “standards” away. Blaze your own surfboard trail. You learn best by doing.
EDIT: the thing about aero comps is that laminates are typically much thicker (multiple layers) than surfboard laminates. Thicker laminates uses much more resin. So there is good motivation in reducing resin content; makes a lighter and stronger laminate. Thick laminates in surfboards would be very heavy. Thats why some surfboard skins are cored with med density foams and soft woods. Each type of core has its strength and weaknesses. Foams are lighter, waterproof, not very stiff, some fatigue, and dampen. Wood is heavier, not waterproof, more stiff, very low fatigue (if kept dry) and has twang. Pic your poison.
i agree 100% percent with what dave just said
and has been saying for at least a couple of years
so there you go guys
its finally on the table on the table
and only 500 views
now if my competitors were playing with all that bagging ,1 to 1 aerosapace stuff
id be very happy little surfboard maker