Different metals are used as a basis in producing various colors. Iron
is the basis for flesh tints, reds and browns. Less iron (in
proportion) is used for yellow and green.
Gold and tin are used as the basis for pinks, roses, carmines, blues,
purples and violets. In mixing colors of iron basis with those of gold
and tin basis the lustre and brilliancy is sometimes impaired.
Experience will show that purple (which has gold or tin as basis) mixed
with black or brown (iron basis) sometimes loses its glaze, on the
other hand the same purple will, as a rule, keep its glaze if mixed
with dark green, owing to the fact that greens have a smaller per cent
of iron. The combining of the two basic metals causes the oxidization,
and this difficulty is hard to remedy. A scroll of gold or silver is
quite a help in this dilemma, they being opaque, defects are easily
covered. Satisfactory tints can be procured by mixing colors of iron
basis as one class and those of gold and tin basis as another.
A piece of china will sometimes come from the kiln with a perfect
glaze, but soon loses its lustre and becomes Matt. This may be due to
the fact that the color is too heavy and not fired long enough.
The china being porous absorbs the natural moisture in the air and
appears to be oxidized. This can be removed with soap and water.
Refiring will prevent a recurrence of this condition.
Special care should be taken with such colors as purples and browns,
that too much oil is not used in mixing. It has a tendency to produce a
dull, undesirable appearance. Keep the colors as dry as possible.
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