I just built this heatstick which uses a thinned-out J.B. Weld to seal the space around the element connections.  1 teaspoon of acetone per both tubes of epoxy worked well to make it pourable, although if I did it again I might up it to 1.5t to make the pouring go a bit faster.  An item for consideration though is that the acetone seems to increase the cure time.

I had my stick drying upright for about 15 hours when I picked it up to check out the curing process.  The epoxy was down at the bottom as expected and did not appear to be liquid so I assumed it was solid enough to dry placed on its side.  Well it really wasn’t, and it flowed a bit down the side of the tube.  This wasn’t a big deal because the wire connections and sides of the element still have a thick coating but if I do this again I will definitely wait a full two days before moving it around.

Before I sealed up the rest of the stick I took it for a test run and it worked as expected.  I plan to use it to fix low mash temperatures, and if it’s strong enough to do step mashes.  It’s only a 1500W element so that may be a tough challenge for it.