Patriot

Ok, this may seem like a no brainer, but I have always wondered how strong a bond would be when gluing a piece of balsa or lite ply over a piece of lite ply that has been given a lite coat of epoxy for fuel proofing. Will the CA stick to it well enough? Or, are you required to use epoxy to glue something to epoxy? Logic tells me I can only use epoxy, as I have been building models for a long time, but truth is, I have never tried to glue CA over epoxy, and have always wondered how well it holds up.

Patriot

CafeenMan

Patriot - the answer is really situational. CA sticks to epoxy just fine, but how strong the bond is I'm not sure. If it's a high-stress area, then I would not put CA directly over epoxy. Sand the epoxy off in the area you want to glue or use epoxy.

If it's a low stress item, then CA directly over the epoxy will probably be fine, but you might want to take some fine sandpaper to the epoxy first to give it a little tooth and wipe it with alcohol to remove that waxy slime that's always on the surface of epoxy after it cures.

mtnlvr

I'm no genious, but epoxy penetrates wood too right? If so, then sanding off the epoxy wouldn't help a whole lot as the epoxy has already taken over and there would be no where for the CA to wick. Does that make any sense?

CafeenMan

mtnlvr - Makes sense to me. But the way I'm thinking is that the CA will at least be sticking to the surface of the wood instead of something else that sticks to the surface of the wood. As I said, to me it's really taken on a specific case basis. I don't use CA at all for construction. The only thing I use it for is hardening holes or as a seam filler in plastic. But I use carpenter's glue and epoxy to build with and I don't fuel proof thing until they're complete, so I never run into this problem.

Patriot

OK, I ran a series of tests.

I took some scrap lite ply that was left over and has a lite coat of epoxy over it. I tried thin, medium and thick.

Thin- It stuck but didn't seem to like it very much. Could have been an unprepped surface though.

Medium- stuck much better, and would use for low stress.

Thick- really took hold when I used with accelerator. It was strong enough to break the wood rather than the joint. I am going to use this method if ever needed. Will probably use to install a new saddle for my servos in the fuse as the inside lite ply is already covered with thin coat of epoxy. I will sand and prep as clean as possible. The servo mount has lots of surface to glue to the lite ply, so it should be just fine.

Patriot