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Fibreglass and carbon

Category: MaterialsCompiled from 3 source threads

Quotes are verbatim and attributed to their original authors.

The fibre layers above and below the core carry the ski's bending and torsional loads. Triaxial fibreglass is the workhorse; carbon and aramid are lighter or stiffer additions that reward experience and punish first-timers.

Start with triax

A layer of triaxial glass (commonly 20–22 oz) above and below the core is the default, and it is roughly half 0° fibre and half ±45°, giving both longitudinal and torsional stiffness. The near-universal advice is to master the process before getting exotic:

"Do a normal triax fiberglass on your first pair to get the rest of the process figured out, then on pair number two, start experimenting… Triax works fine for almost all applications."
— twizzstyle · thread #4334, "Idea for a layup, involving carbon and aramid"

As another put it about jumping straight to carbon and aramid: "Way stiff, way heavy, way expensive. Get your process down then get fancy" (Vinman).

Adding carbon

Carbon is roughly three times stiffer than glass, so builders use uni-directional carbon with biax glass (for example 12 oz biax glass with 5–7 oz uni carbon) for a lighter, stiffer, poppier ski, often with an extra patch of glass underfoot. The key insight is counter-intuitive:

"The main weight saving in a carbon ski comes from the thinner core, not the lighter laminate. It's actually really rather hard to design a carbon ski as carbon is just really stiff so the core needs to be really thin to get some flex… design the core profile based on your layup, and not the other way round."
— SleepingAwake · thread #1988, "fiberglass and carbon proportions"

Aramid and Kevlar

Aramid resists tearing and impact, but it is not a stiffness material and it soaks up resin:

"Aramid fibers demand too much resin, adding weight. The only reason to use a certain amount of Aramid in a layup is vibration dampening."
— Richuk · thread #4334, "carbon and aramid"

It is also awkward to finish at the edges — the trick is to "soak fuzzy sanded kevlar ends with super glue, then cut with a razor blade using a sawing motion" (24Dave).

Source threads