You need to heat it up to about 180 dergrees for about 15min or so and let it cool and then you can sand it. But you also need to scuff up the area's that the bonder is going to be applied on with some 80 grit sand paper. After it is all set up I would use a little body filler to cover the panel bonder and to smooth it out because if you just prime over panel bonder and then paint it your primer will shrink back and you will see exactly where you applied 8115. Not to mention the fact you will be really pissed.
i friend that works at a body shop is doing it, and wasnt sure what to use since it was urethane, and i know some guys on here have done what im wanting to do but i didnt know what material to use so me and my frined are both asking around on the materials that would last