Hi, I’m making a high performance shortboard and have a few questions about the fiberglass cloth.
I like the weight of the standard 4E + 4E deck/4E bottom but they are far too fragile for my liking. I will be buying all materials of shapers manufactures Australia which have various types of 4oz cloth. I was thinking of using the standard 4oz layup but in S class cloth but shapers have these new cloths, one called Exo Glass and one called SX glass. I will be using a PU blank by the way. Does anybody know anything about these new glasses and which glass will be the strongest. Also, are there any flexural differences between the glasses?
The strongest 4 oz fiberglass cloth is 5oz fiberglass cloth. It’s just that most backyarders don’t know that they make such a thing. Otherwise I prefer BGF Aerialite, JPS, and Hexcel. You can’t go wrong with any of the three. Chinese and Korean "knock-offs don’t get it. If a supplier does not specify what brand their cloth is; You can assume it is other than the above. Their are also a couple of minor manufacturers in the US whose names don’t come to mind, that are also pretty good quality.
If you’re using PU resin then the weakest link in any 4oz lamination will be the resin, not the cloth.
You’re using a PU core so that’s going to add to the stability of your end product. If you upgrade to epoxy and you post cure it that will probably be all you need unless you’re constantly abusing your board by throwing it in the back of your truck without a bag or banging into stuff during handling.
S-cloth is stronger than E-cloth but it’s also stiffer. I know some builders use S-cloth with PU resin but I think epoxy is actually a better match because it isn’t as stiff/brittle as PU resin. One possibility you could consider is an E-cloth lamination with S-cloth deck patch.
And it’s simple to expain: elongation to break. All material under stress start to deform ie elongation when stretched. E glass is around 3% as most surfboard PE resin, S glass and epoxy are around 5%, so can be stretched more before break. For composits first rule is to use a resin with higher elongation to break than reinforcement fiber.