15 minute Epoxy is heating the plastic!

Last night, I was working on a P-70. To give nose weight, I tend to use 15 minute epoxy and a few spare metal peices to give weight. The metal is most usally a screw and nut. But with the P-70 nose, there is limited room, so I used a pair of wire terminals.

For the first time using this method, I had the problem of the epoxy heating up the plastic. It got so warm, that the plastic began to get rather soft. So I put the part into my freezer for a few moments. That cooled it off, but I am worried about why it happened. [%-)]

Anyone out there know anything about this problem?

Epoxy curing is an exothermic reaction—it generates heat. In the case of epoxy, sometimes more than enough heat to melt styrene, or burn your hand. The total amount of heat is volume dependent. A cupful of most epoxies will generate enough heat to make the container uncomfortably warm, or melt it if it’s in a plastic container. Small amounts of epoxy don’t generate as much total heat.

You used too much epoxy. Don’t fill the cavity, use only enough to bond the two materials together.