Didn't see an actual chart in our search so we thought we'd share this most recent testing data. This graph is provided by the good folks over at JPS. It's probably info that most guys have known for years but it's nice to see some numerical values. The complete blog is at www.compositecorner.wordpress.com.
May be interesting but not for braking. Surfboards brake because of localized buckling of compressed skin and uncapability of foam to stabilise it. Overall stiffness, mostly resin contibution in compression, is the key (and foam shear strengh). Tensil test, an easy and effective classic test for homogenous isotropic material, isn't really interesting here. 4 point impact flexural test is more appropriate. Just my opinion
Sorry for my frenglish.
How about resistance to shatters and compression dings?
What is the 4oz Direct Size cloth??? What is this stuff???
Direct Sized fiberglass undergoes a finishing process which allows for increased tensile strength and a brighter/whiter finished product. It's a pretty cool fiberglass that guys either love or hate. It certainly gives the board a specific flex and is very white but it does cost a little bit more.
http://shop.fiberglasshawaii.com/fabrics/surfboard_cloth/direct_size-214
I have been using the D-size cloth for two years.
Super strong.
I think just as strong as S-glass.
Double D-size decks are rock hard and light.
Price is just slightly more than E-glass.
The downside is the weave falls apart easily. Very stringy. Lapping technique is key.
It also is very slippery, meaning it slides and cloth shifts easily.
Overall I'm happy with it.
Thanks Fiberglass Hi. for showing that chart. It confirms what I already beleived.
It would be nice to see relative cost and compared to Fiberglass Tensile Strength to determine, dollar to dollar what is the best value. If we by E, S wraped, D-size which would be the best value in terms of price. Later we can factor in other points such as the glass being too string, doesn't wet out well, not good for color lams, etc. (For now, I normally buy what is in the bargin bin at FGH.)
My two cents.
D
re read what Lemat wrote.
Tensile strength is a measure of when a strand of fiber will snap and break when pulled on. Think a guitar string that is over tightened. Tensile strength isn't the most important measure of laminating cloth to surfboard making. What was the last time you saw a surfboard pulled appart, nose from tail?
Stiffness is applicable. Toughness ( the resistance to scuffing and abrasion) is also important. Flexibility and resilience (the ability to recover from deformation) are also important. But unless you are making parachute cord, tensile strength is secondary to shear.
Elasticity should be paid attention to. Does the fiber strech and than recover? When fiberglass fails, it is more shear that failed. Along with compression of the foam core.
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A is compression
B is tension
C is shear
Shear forces are when your board hits a rock. The nose isnt pulled from the tail, but a perpendicular force punches into the skin.
From what I can gather from the net, normally the fiberglass yarns are coated with something making them slippery when woven. The coating is removed with heat after weaving and another finish is applied which makes the glass fiber bond with resin (volane or silane the most common). The direct sizing differ in that it doesn't use any special coat when woven, and thus not need to be heat threated which to somedegree weaken the glass fiber. I'm guessing the direct size finish is sufficent slippery to be woven (ref. Barry's description of the cloth being slippery) while having the required molecules for the resin to bond to.
I'll second Barry's note about the direct size cloth, my chief complaint is that the stuff unravels while you are working with it… threads come out of the weave pretty much no matter what you do. I have a roll of the stuff (in 4 oz) if anybody in San Diego area wants to try it, just swing on by.
My go-to favorite these days is 5 oz cloth (actually its 4.7 but who is counting)…drapes nice like 4 ounce but strong like 6 oz… best of both worlds kind of thing from my perspective.