MEDIUMS AND ADHESIVES 31
Lac (see also Resins and Shellac), This resin is not a natural exudate from a
tree but is produced by an insect belonging to the Coccidae or scale insect family,
Tacchardia lacca. Like the cochineal insect, these produce a red dye which was
formerly valued both in India and in Europe. The tree, Butea frondosa Roxb.,
which is still one of the most important hosts, is referred to in Sanskrit writings as
'Lakshatarn, the tree which nourishes a hundred thousand insects,* and in the
writings of ^Elian, about 250 A.D., there is reference to the insect yielding a red
coloring matter. Mention of the use of lac in varnish is made in the 'Ami-Akbari,'
1590 A.D., which tells of the decorating of the imperial palace. The dye was used
in Spain and in Provence as early as 1220, and is mentioned in recipes for rose-
colored lake. The Paduan MS. (Merrifield, II, 688) speaks of the colorless resin
left after the extraction of the dye, but apparently its use as a varnish ingredient
was unknown in Europe until the XVI century.
The insect attaches itself to various trees of the acacia family (particularly
Ficus religiosa Linn.) for feeding and breeding. Both hard- and soft-woods may act
as hosts, but generally soft, non-resinous trees are preferred. The insects fasten
themselves to twigs and branches and produce a scaly covering consisting of an
amber-like material which is the basis of shellac varnish. The secretion forms a
kind of cocoon, and as the separate exudations coalesce, a continuous layer is
deposited over the twig. This resinous secretion is collected in June and November
and is dried and ground. It is then washed free of coloring matter and is filtered
and dried quickly, for it grows dark on exposure. The lac is graded as to size and
the largest particles, * seed-lac/ go1"to make the best grade of shellac varnish (see
Shellac). Lac, dyed yellow, is used in the East Indies for ornaments. It is an
important ingredient in sealing-wax. At present, the largest portion of the total
lac production is taken by the electrical and gramophone industries.
Lacquer (see also Resins) is a broadly used term. It has been applied to paints
or varnishes that dry with a high gloss. It has been applied, also, to coatings made
from shellac. In modern commercial usage it indicates a coating material that
dries by evaporation of the solvent. Coatings made from synthetic resins and
cellulose derivatives are commonly known in the trade as lacquers. Such coatings
are usually clear but they may be pigmented or dyed.
More strictly, and in the fine arts, c lacquer * is used for a natural resinous
exudation from the tree, Rhus Fernicifera DC. In China, where the art of lac-
quering originated, the tree is called Tsichou (varnish tree) and in Japan, where
the art was imported and reached its highest development, it is known as Urushi
No-Ki* There are other lacquers from Burma, Indo-China, and Formosa. These
are like the Chinese and Japanese variety, though Burmese lacquer dries more
slowly and is said to be free from the irritating effect on the skin, which is the
European worker's objection to the Japanese product. The tree, indigenous to
China and cultivated in Japan at least since the VI century, is tapped when
about ten years old, horizontal incisions being made in the bark. The resin is a