I have been following this discussion since it started, and posted a reply regarding my use of epoxy, since I have not tried the poly. I am still not convienced that poly is worth trying for several reasons. One is the fact that the balsa has to be sealed prior to putting down the glass to avoid soaking up a lot of water, My second concern is the bond between the sealer and the glass cloth. Those advacating the use of the WBpoly don't mention the application of the first coat to ensure the glass is firmly down on the surface, and not floating in the wet poly. I know this can be a factor using epoxy. If the epoxy resin is applied too heavy, and not squeeged out as much as possible, the fabric may float up. Then when sanded, you go through it. Finally, after three or four coats of poly is applied, I assume one still has to sand it down to the surface to remove any imperfections. then you start with the prirmer?

And as was mentioned before, it cures (dries out completely) for a week or more, and continues to shrink for even longer. Not for me. The epoxies mentioned in several different posts all cure chemically, and after about 24 hours, sand very easily, some maybe better than others. There will never be a problem with bonding, as with epoxy that is not an issue. Idon't think anyone here will argue that one. Epoxy will have a harder finish.

As for the difference in weight between a .5 oz glass and a .75 oz glass, I doubt it will really make a noticable difference. The final finsih might be .001" thicker, and that won't be much. What WILL make a differance will be how much you sand either type of finish in preparation for your final color application.

Dash