Posted by les on September 23, 2003 at 02:57:16:
In Reply to: What's the difference between Biaxial cloth and E-glass? posted by ken on June 20, 2003 at 20:11:29:
: I have been surfing websites pertaining to fiberglassing. I see S-glass, biaxial cloth, and E-glass. I thought that if you arranged the fibers in a 45/45 direction as opposed to regular cloth, then you got E-glass.
: Then I ran into a site that sold biaxial glass seperatly than the E-glass. Now I am really confused, please help.
: If that is not enough, I ran into a place selling chopped mat with a statement "do not use with epoxy resin". Now I must ask if there is a difference using epoxy resin as opposed to fiberglass resin (as far as the cloth is concerned).
1st, biaxel cloth is where the weave is set at 45 deg to each other rather than 90deg as is standard cloth. It is best used in a tape form when glassing a joint ( stitch and glue) as you have the full array of fibres crossing it. Ordinary tape only has 50% of fibres crossing the join so is only doing half the job!. S glass. K glass and e glass pertain to the glass fibres themselves. The stiffer the glass cloth the finer the strands used but are stronger. Each has its own application. Go to a site like hi modulus.co.nz ( I think I spelt it right ) and they will explain it better. As for glass matt, this not used for epoxies as they have a wetting out agent that is not activated by it. It is used primarily for laminating using polyester or vinyl ester resins in molding as in production boats made in molds. It can also be used with glass cloth on polester based foams ( epoxy's will disolve these, as will polyesters will desolve styrofoams which are used in other applications ( ie home built aircraft for instance )
Epoxy is lighter but more expensive than polyester and is used in timber construction, where as polyester is used for mass production and the weight of the final product is not that critcal. It was pointed out in another query about waxes in resin and so forth. polyesters have waxes and are not to be to worried about as the laminating process is a chemical bond where as epoxys are a physical bond, so any further laminating in epoxy on epoxy the surface should be roughend. You can bond epoxy on to polyester but not the other way round.
When glassing a timber hull, the timber should be sealed with epoxy to stop gassing out and allowed to cure then filled, faired and then roughend up by sanding then glassed over. If glass is applied straight on to bare timber the resin will soak into the timber, air bubbles could appear under the cloth (gassing out) and the laminate will always appear resin hungry - not a good laminate at all!
I hope this helps.