Minium Or Saturnine Red Is An Ancient Pigment By Some Old Writers
:
ON THE PRIMARY, RED.
confounded with cinnabar, and termed Sinoper or Synoper. It is an oxide
of uncertain composition, prepared by subjecting massicot to the heat of
a furnace with an expanded surface and free accession of air. Of a
scarlet colour and fine hue, it is warmer than common vermilion, whose
body and opacity it possesses, and with which it was once customary to
mix it. Bright, but not so vivid as the iodide of mercury, it is more
durable, although far less so than vermilion. When pure and alone, light
does not affect its colour, which soon flies, however, on being mixed
with white lead or any preparation of that metal. By impure air, red
lead is blackened and ultimately metallized.
On account of its extreme fugacity when compounded with white lead, this
red cannot be used in tints; but employed, unmixed with other pigments,
in simple varnish or oil not rendered drying by any metallic oxide, it
may stand a long time under favourable circumstances. It is an excellent
dryer in oil, and has often been used as a siccative with other colours,
but it cannot safely be so employed except with the ochres, earths, and
blacks in general. Oils, varnishes, and, in some measure, strong
mucilages, are preventive of chemical action in the compounding of
colours, by intervening and clothing the particles of pigments; and
hence heterogeneous and injudicious tints and mixtures have sometimes
stood well, but are not to be relied upon in practice. Altogether, red
lead is a dangerous pigment in any but skilled hands, and has naturally
had a variable character for permanence. It is frequently adulterated
with earthy substances, such as brickdust, red ochre, and colcotha.
TTITLE VERMILIONS.