Lac Dye Cas 60687 93 6 Foreverest - Chinaprice: contact company for price
turns bluish, dark red. Lac dye is soluble in ethyl alcohol
and methyl alcohol, also in acetone and acetic acid. Lac dye
is partially soluble in water and ether. Lac dye is very
lightfast and resistant to temperature, it melts at 180° C
and decomposes at approx. 230° C.
Lac dye may be used for dying of textiles, such as silk,
cotton, wool. It may also be used for oil painting, in
shellac varnishes and possibly in watercolours.
Lac dye is obtained from the females and eggs of the insects
known as Coccus lacca, which infest various trees,
especially fig trees, indigenous to Asia and China. They,
and kermes and cochineal insects, are of a type commonly
called "shield-louse", as they are small and round with a
shield on the back. Female lac insects have vestigial wings
and legs and spend their whole life gathered in large
clusters on host plants. When lac dye is harvested, its
animal origin is virtually unrecognisable, because it is a
solid substance made up of bodies of female insects which
are dead, each with some 200 to 500 unhatched eggs, all
surrounded by a brown-red, hardened exudation. Individual
insects are not visible, and the whole substance looks like
some form of growth on the host plant. It is collected by
breaking off lac-bearing branches before the larvae hatch.
Some lac is left, and at swarming time the larvae of minute
size can be seen for a few days moving about to find a place
on the tree to settle and feed.
In ancient times Asiatics, who were able to observe the life
cycle, knew that lac was a substance of animal origin, so
various names meaning "little worm" were developed for lacca
and similar insects. To Europeans, however, lac appeared to
be part of the sticks on which it was imported, thus the
name coccus (berry or acorn) was attached to lac and later
to the live insects, a misnomer for which the ancient Greeks
and Romans are held responsible.
Discussion on the confused nomenclature connected with a
number of red pigments has been undertaken by other writers.
The origin of the links between Latin coccus and granum and
English grain (all of which are associated with the idea
that lac was a seed or berry), and the links between kermes
and vermiculum (both meaning little worm) are to be found
during the medieval period and they are ably discussed by
Thompson. When continuing the discussion with special
reference to seventeenth-century England, it is possible to
ignore the name grain, which, apart from its specialised use
in textile dyeing, was obsolete. Nevertheless, the
seventeenth century presents an additional problem in that
the words cinnabar and sinopiawere wrongly associated with
the name sinoper lake, which may have been a development of
the medieval name cynople (Latin sinopia) mentioned by
Sinoper lake and the variation topias are to be found in
sources dating from the late sixteenth and early seventeenth
centuries. The composition of both is uncertain; Thompson
states that medieval cynople was a composite lake, and it
seems that sinoper may have been similar, for that mentioned
in B.M. MS. Sloane 1394 was derived from the dye in scarlet
- Posted By: Foreverest Resources Ltd.
- Phone: 865925105533
- Address: Flat 1604, No. 36, Lianbinli, Siming Dist, Xiamen,, Xiamen, China
- Website: http://www.rosinester.biz
Published date: August 30, 2013 -
- Business Description: FOREVEREST is the leading supplier of pine chemicals, such as gum rosin
& derivative, gum turpentine & derivative products and other pine
chemicals. Manufacturing by renewable and environmentally friendly raw
materials since 1988.
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