lake
A term used with reference to any of a large group
of organic pigments that are generally bright in
color and are more or less translucent when in the
form of an oil paint. Lakes are obtained by
precipitating dyestuffs and other coloring
matters, e.g., cochineal, madder, logwood extract,
etc., onto a substrate in the presence of tannic
acid, casein, sodium phosphate, etc., or with a
metallic hydroxide. Aluminum hydroxide, for
example, reacts with many soluble organic coloring
matters, precipitating them as so-called lakes in
cloth printing and dyeing, with the hydroxide
acting as the mordant; the same dye, however, can
produce different colored lakes depending on the
mordant employed. Because many salts of calcium,
chromium, magnesium, tin, zinc, etc., are used in
producing lakes, a great number of pigments can be
obtained. Substrates used include alumina, which
gives a pigment that is rich and transparent in
color, such as those used in printing inks; china
clay, where a light, soft material with bulk and
good suspension properties is required; barytes,
which are used in the manufacture of paint; blanc
fixe, which is usually a more finely divided
baryte than the natural crystalline ones; and
green earth and precipitated hydroxide of iron,
which are used according to color requirements.
Many excellent pigments having good light fastness
are now made from artificial dyestuffs; therefore,
because they are expensive and/or insufficiently
light fast, many lakes formerly produced from
natural dyestuffs are no longer in demand.
The term "lake" may derive from the Italian
"lacca," used by medieval Italian craftsmen to
indicate the scum they removed from their dye vats
and sold to painters. The Italian word, in turn,
is related to "lac," which derives from the
Sanskrit. See: LAC
. (17 , 195 )
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