I use one of these, although a lot of beekeepers use pre-wired foundation and believe this
procedure is not necessary.  One advantage is that the horizontal wires "locate" the foundation
closer to the center of the frame, resulting in more uniform comb.

I  watch to see the wire melts the wax enough to "stick" to the surface, then I release the
switch. Sometimes the wire is entirely embedded, sometimes just "tacked" to the surface.
After releasing the switch, I sometimes use the embedding tool's brass ends to push the
already warm wire down a bit into the wax, to get it embedded more fully.

By the way, I did not like the elementary "switch" on the embedder, which was basically a
soft brass strip that acted like a spring when pushed against a cadmium plated screw to
close the circuit.  I ripped it out and replaced it with a levered micro-switch  that I got from
Radio Shack for a buck or two.  The brass strip develops some pitting when it is in use, and
sometimes doesn't close the circuit when held down, which I found annoying.  The microswitch,
with silver plated contacts, works much better.

C. Crowell
Hightstown, NJ