I’ve melted and reformed blocks of blue machinable wax without harm.
That’s one of the advantages of this material - no waste. If you
throw in all the chips from cutting it (making sure not to pick up
contaminants) this will introduce air that needs some time to work
its way out, but it eventually does result in a block with pretty
much the same physical properties as the original.
if it is safe to melt them down and let the wax re-harden, what is the best technique (can I do it on the stovetop without burning/overheating it?), and when I pour it into a bigger container, should I line the container with something to prevent it from sticking in there?
I wouldn’t recommend stovetop melting for wax. There’s too much
danger of overheating, which at best will harm the material and at
worst will result in a fire. Use an electrically controlled pot, like
a deep-fryer instead, preferably with an infinite range control (not
just low, medium and high) so you can control the temperature
accurately.
If this is the same material I’ve used, there’s no need to line a
steel container - it doesn’t stick, and shrinks quite a bit allowing
easy removal. I’ve cast it into a steel pipe to get cylinders for
4-axis carving, and after cooling they drop right out. Flat slabs are
challenging to cast, though - due to the high shrinkage, it tends to
warp a lot as it cools.
Andrew Werby