screw holes

I'm building my gator duck boat and I had a quick question about the holes where I used screws. I see everyone mixes wood flour into the epoxy, since I'm going to be covering the hull with fiberglass what is the purpose of mixing in wood flour ? Can I just use the epoxy to fill the holes or is there something wrong with that ? I guess if I have to use the fine sawdust I can make some by simply sanding down some scrap wood but if I don't have to I'd rather not. Thanks for the help guys

Sab

 

Not everyone uses wood flour. Many of us are completely against it. Fumed silica is what professionals normally use. It mixes easily and adheres better.

 

sab...gator duck boat, I like the sounds of that. Might you be from the southlands? Bayou country? Are you using epoxy or polyester for the glassing? If its polyester you can use just use plain ol bondo or fumed sllica (cabosil) mixed into the resin. With epoxy I agree with gonzo fumed silica rules. Just make sure you work it into the holes real well. Have fun building.................................g

 

Instead of using wood flour or worse, sanding dust from the belt sander, use plain old cooking flour, preferably rice, but wheat or corn flour work well too. It's a lot cheaper and has similar physical properties. Silica is the preferred choice among pro's, though must will use some wood flour for coloring in joints. To answer your question, straight epoxy will work, but you'll want so "reinforcement" in the epoxy, to stiffen it up a bit, so silica, wood flour, cooking flour, milled fibers, etc. are all employed. On a screw hole I'll use milled fibers and silica. The milled fibers grab the screw better then wood or cooking flour and the silica controls the viscosity of the mix.

 

I use milled fibers and silica mix too. The fibers make it less brittle.

 

Thanks for the responses guys, I guess it's silica...if I'm going this far might as well do it right. Where would I find it ? Anywhere on the web, or just google silica ?

 

Bulk silica prices are about the same at the usual sources, so shop the online supply stores and see how you fair.