Enamels and enamelling; an introduction to the preparation and ...

For violet : manganese oxide.
For brown : ferric oxide.
PIGMENTS. 49
For black : ferrous oxide in large proportion.
The above list mentions only the principal fundamental
colours obtainable by the aid of the pigments specified. These
colours are, however, insufficient by far for the purposes of
painting in enamel, the artist in this branch requiring as large
a range of colours as his other confreres of the brush in order
to be able to obtain any desired shade. Now, the latter object
can only be attained by employing larger or smaller propor-
tions of the pigmentary materials, and thereby producing a
graduated scale of shades of the pure colours ; and when it is
desired to have mixed colours the chemical composition of the
pigments will have to be modified in certain ways, or special
artifices must be resorted to.
As a more suitable opportunity of considering the latter
eventualities will arise when the process of enamelling is under
discussion the matter may be left over until then, and atten-
tion now directed to the purely chemical side of the question,
namely, the preparation of the various pigments, not omitting
to mention that the use of chemically pure materials enables
one to obtain any desired shade much more easily than when
special attention has to be bestowed on the presence of
impurities accompanying the true active principles
pigments employed.
YELLOW PIGMENTS.
in the
The sole means of producing a pure yellow in enamels is
by the aid of antimony oxide, potassium antimonite or silver
oxide ;
for cheaper qualities, however, ferric oxide is also used,
though, strictly speaking, the colour obtained is not yellow at
all, but a peculiar reddish brown, such as may be seen in an
intense form in brown wine bottles.