Well I finaly got around this week to trying this epoxy and here are my non-sceintific findings as of Wednesday.

US Composites 635 Thin Epoxy Resin System with 2:1 Ratio Slow Epoxy Hardener #556
First use: Saturday, Laying glass on bare wood
Second use: Monday, fill coat on fully cured (Raka) epoxy and bare wood saturation
Third Use: Tuesday, fill coat over Mondays coat and bare wood saturation

Laying Glass: This epoxy is nice and thin. It had no problem soaking through 2 layers of 6 oz cloth and saturating Luan. However, it foams easily and made it hard to tell if I was starving the glass or if it was just foam. This was no suprise, as when mixing, bubbles (like soap bubbles) were rising out of the mixing cup.

Cure speed: SLOW. Much slower than Raka or MAS. The first two uses took two days heating my shop to 75 to lose tack (however nights were cool and I did not keep the fire going at night). Third use was tack free in 24 hrs. but day and night were much warmer (shop was still over 60 this morning). The puddle left in my mixing cup from first use is still soft enough to fold in half with no signs of braking.

Blush: None apparent.

Clarity: Seems about the same as Raka, however foaming could lead to cloudiness.

Smell: About the same as Raka

Conclusion: Although thin, I did not like this epoxy working with glass. The foaming bugged me and led to too much working of the epoxy on the glass. The foaming wasn't as much a nusance on the bare wood as it was easily brushed out. Foaming didn't seem to be a problem on fill coats (less friction?). The cure time can be limiting. The company does not recomend use below 65 and I see why. I would heed this warning. They do make med. and fast hardeners but they do not use the 2:1 ratio and I know I would screw up. With my heated shop I could keep it warm enough but don't always like working at 75. And even with it warm, it may be a while before I can sand.
So would I use it again? At the price it sells for it's hard to pass up. I will not use it for laying glass but it looks like an economical way to do fill coats. Just crank up the heat and start work at the apex. Besides putting off sanding is not the worst thing:)

David