Hi Stephen,

Don't confuse Kevlar 49 (used for lamination) with Kevlar 29 (a fabric used for ballistic strength). They have MUCH different properties and purposes, and neither is a substiute for the other.

Kevlar 49 is used with epoxy, vinylester, or polyester resins in traditional wet lay-up or vacuum-molding techniques for solid or sandwich constructions. It can produce laminates 10-30% lighter than equivalent all-fiberglass layups, but must be properly designed and fabricated to take advantages of it's unique properties. While a Kevlar 49 laminate is tougher than fiberglass (and, I emphasize the rigourous engineering definition of "toughness"), it is far from bulletproof. As for abrasion resistant, it will resist punctures better than fiberglass, but will fuzz and become ugly quickly. It will be very difficult to repair once fuzzed, and ain't a real treat to use in the first place.

Kevlar 29 is a fabric, not designed to be used in a general-purpose laminate. It is sewn into multi-layer "laminates", but not impregnated. I don't profess to know or understand the physics of how it provides ballistic strength, but suffice it to say it works wonders in bulletproof vests, chainsaw "chaps", splinter and fragmentation containment "armor", etc. But, it is not intended as a lamination material, except as a replacemnt for mat to form solid cores in such things as boat hulls.

Much of this information is contained in Du Pont Technical Bulletin K-6 titled "Kevlar 49 Aramid for Boat-Hull Construction". It's dated 1981, and I don't know if it, or an update, is available any more. But, if you can track down a similar source, it will provide you with a ton of information.

Roger, roger on Aircraft Spruce as a source of laminate materials. I've used their 1.5 oz fiberglass cloth for years as an exterior skin on my 'yaks. Works good.

Pete