Regarding the corrosion of aluminum in bonding with epoxy..one of the
homebuilt aircraft was put together using the method of sanding the surface
through the still "wet" epoxy. The theory was the epoxy on the sanding
surface would minimize the corrosion.

On Sun, 16 Oct 2005 13:35:55 +0200, GeoffC wrote:

dazed and confuzzed wrote:


Aluminum is like silver. It oxidizes almost instantaneously.

It is this thin layer that fails when gluing parts. The adhesive bonds
to the oxide layer and the oxide fails, not the glue.

I wonder how the Lotus Elise stays together then? It has an aluminium
tub-chassis, constructed from aluminium extrusions bonded together with
epoxy resin.

It's not that you can't epoxy aluminum. Of course you can. You just have
to do good surface preparation first.

There are products designed for this. Someone mentioned an etch sold by
West Systems or something like that. I think there is something called
Marine Tex that bonds well to aluminum.

But in the OP's case, I would just use JB-weld to stick the piece back in,
then put a single layer of fiberglass/epoxy over the outside of the broken
piece, then paint. I would sand the area in the immediate vicinity of the
break down to bare metal and clean with acetone or alcohol prior to
applying the epoxy.

Surface preparation is EVERYTHING in bonding applications.

--Mac