shellac
A resinous secretion of the insect, Tachardia
lacca, which breeds on the twigs of certain Indian
trees. It was originally used as a source of
dyestuff, but is now used almost entirely for its
content of resinous matter. Shellac has a
softening temperature of 60 to 75° C., but
decomposes if heated much above 100° C. It
is soluble in alcohol, except for about 4% wax,
which is insoluble in cold alcohol. It represents
the most highly refined form of LAC and is prepared
in the form of thin orange or yellow flakes. The
term is also used with reference to the varnish
prepared by dissolving shellac in alcohol. Shellac
is used in the manufacture of leather, in
lithography, in the preparation of finishing
sizes, etc. See a1so: SHELLAC SIZE . (233 , 235 )
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