I did some experiments with the light glass/deft technique and my old glass/resin to determine strength and weight. I also compared them to monocoat for a frame of reference.
I used a powder scale that measures in grains because my 4” X 4” test pieces were so light I couldn’t get significant measurements on the electronic scale. I converted to ounces but I’m just going to give relative values. My paint could have been lighter too. This was 4 coats of lacquer. I think the resin would also be heavier in practice since I was able to sand it down farther than might be practical on curved surfaces. The deft is faster, easier and you don’t have to worry about pot life.
These are not meant to be absolute values. I just wanted to get an idea of what to expect.
These numbers are for materials only (no wood) for a single test piece. Due to different amounts and materials (or math errors) the results could differ.
Monocoat = .22 oz per square foot.
Glass/deft = .36 oz per square foot. With paint = .67 oz per square foot.
Glass/resin = .78 oz per square foot. With paint = 1.09 oz per square foot.
I knew the deft would be lighter than resin. Half the weight is not bad. Since you can’t paint over monocoat that number is meaningless really. I’ll have to try silkspan/dope sometime just for grins.
I tested the strength by dropping lead weights from various heights. The resin is definitely stronger (perhaps as much as twice as resistant), but the glass/deft protects well too. Another coat or two might help, but I’m not sure it’s worth the weight.
Unless I really need the protection or fuel proofing that resin provides I will never use it for glassing again – the deft is so much easier to work with and lighter too. My thanks to Gray Beard for this tip.