- Sun Aug 30, 2009 11:38 am
Strength of the fibers.
Keep in mind we're talking about pretty small differences that are mostly discernible when goop is used in large quantities, like on power boats, sail boats, etc. I've used nothing but wood flour out of my stationary belt sander as my exclusive filler for quite a few boats, and only recently began using "real" fillers again, and that's mostly so I'll know a little bit about 'em. But I believe that for our purposes, free wood flour works fine, and only begs the question of how much to add, which is only a matter of what you're hoping to accomplish with it. Glue filler? Mustard consistency. Fillets? Peanut butter. Etc., etc.
Also, wood flour being a natural organic material, it's naturally inconsistent, and fumed silica being synthetic, is very consistent. This means thickened epoxy made with fumed silica will "go on" smoother and "creamier" than that made with wood flour. The finer the wood flour, the smoother it'll get. Mix up some thickened epoxy using coarser sawdust, or anything else that strikes your fancy, next time you have some leftover in a cup that's going to waste, maybe try to apply it something disposable, and see what cures out.