Confectioner's glaze, also called "pharmaceutical glaze," "resinous
glaze," "pure food glaze" and "natural glaze," is a common ingredient in
candies and pills. By any name, it's the same ingredient as shellac,
the chemical that they sell in hardware stores and that is used for
sealing and varnishing wood floors (and previously used in electronics).
Shellac is actually a chemical secreted by female lac bugs (Laccifer lacca),
a type of "scale insect," in order to form sheltering tunnels as they
travel along the outside of trees. It is extracted for industrial use by
scraping bark, bugs and tunnels off of trees in Asian forests and into
canvas tubes.
The tubes are then heated over a flame until the
shellac melts and seeps out of the canvas, after which it is dried into
flakes for sale. Before use in food or as varnish, the shellac must be
re-dissolved in denatured alcohol.
Instead of shellac, some food producers use a corn protein called zein.
Sources:
http://www.evilmadscientist.com
http://en.wikipedia.org