Re: when using epoxy what is the best way to buildup?
If working with continual nonstop layers I've put cloth on cloth on cloth ok
but if stopping between layups I hit it with a block to knock down sharp points and start with matt again, cloth will not lay flat unless the previous layers are still wet. But that was with poly.
Cheaper untreated cloth feels like cheap polyester fabric, pull it across your palm and it catches on the skin, higher quality cloth has a smooth feel to it like satin.
Just found this,
"When fiberglass cloth comes off the loom it is said to be ?in the greige? [pronounced grey]. In order to be compatible with resin systems it must first be heat cleaned to remove oils and sizing needed for weaving and then treated in a chemical bath, called ?finishing.? Finishing formulations are proprietary recipes that enhance bonding with the type of resin to be used. One of the earliest fomulations that is still in use is called Volan, which employs compounds of chromium. We do not recommend the use of Volan finishes because of the chromium content. Chromium is a toxic heavy metal that is considered a strategic material by the military and much of it is imported from Africa. Potential problems are evident! It also imparts a green cast to the fiberglass and the resulting laminate is generally rather grey and dirty looking. Silane finishes produce a clearer laminate and avoid the chrome problems.
Our preferred silane finish from BGF is called 497A. It was developed for critical aerospace applications and is compatible with epoxy, vinylester, and polyester resins. We occasionally have fabrics with 627 finish, also a general-purpose silane. Our fabrics that are made by Hexcel-Schwebel have a CS-767 finish, which we believe to be comparable to the BGF finishes. Very occasionally we will have some material that is finished specifically for one resin system, usually epoxy. In those instances we are careful to assure that a potential buyer is using the correct resin before making a sale.
Fiberglass finishes are degraded by environmental conditions such as moisture or even humidity and they deteriorate to some degree just with time. The 497A finish has especially good longevity, which is one of the reasons we prefer it. While deterioration begins as soon as finishing is completed, there is no significant loss of physical properties over the first year or two, provided the fabric has been wrapped in plastic and protected from high heat and humidity. I would be careful about using fiberglass more than three years old and would probably not use it after five years for any critical application without running some tests first."
Hehehe, my glass is well over 10 yrs old. Works for me.!
