: Bill, I know we all learned that aluminum oxide limited bond
: strength, but I'm not sure that that is always true. The H8000
: is reported to have a shear strength of 3000-3500 psi on both
: steel and aluminum, and the T-Peel is actually higher on
: aluminum than steel. There could be lots of reasons for this,
: but it does suggest that the oxide is not the limiting factor.
: Perhaps the adhesive penetrates the aluminum oxide layer. Also,
: I don't know what the definition of structural is, but at 3000
: psi this stuff may qualify.

: Is this adhesive really suitable for kayak frames? I don't know
: yet-I'll report back in a few years.

: Jeff

Hi Jeff,

The published strengths are when using bare aluminum, the trick is getting the aluminum bare (which isn't really hard, just dirty) and keeping it that way till it's glued.

I've painted and glued aluminum and sometimes it works and sometimes when it's done exactly the same way it fails. No real reason why other than the oxides form quicker it seems in some alloys and/or possibly weather issues for how the oxides form.

The aircraft industry has a published method that works, but is too expensive for home use and it's licensed anyway. A guy named Molt Taylor came up with a method for homebuilt aircaft of sanding the aluminum while in a bath of diluted epoxy that seems to work for home built aircraft, the epoxy bath keeps the oxides from forming while they are being sanded away.

Bill H.