The three things on which the quality of good paint
depends are good pigment, good vehicles, and good preparation.

The pigments used are of mineral, chemical, and vegetable origin. The
term _pigment_ technically means the powdered substance which, when
mixed with a vehicle, as oil, becomes _paint_. The most important
pigments now used are artificial products, chiefly chemical compounds,
including chemical preparations of natural mineral earths.

As a rule, the colors made from earths may be classed as all
permanent; those from chemicals, permanent or not, as the case may be;
and those of vegetable origin fugitive, with few exceptions. Some
colors are good when used as water colors, and bad when used in oil.
Further on I will speak of the fugitiveness and permanency of colors
in detail. I wish here to emphasize the fact that the origin of the
material of which the pigment is made has much to do with the sort of
work that that pigment will do, and with the permanency of the effect
which is produced; and therefore that while a paint may look like
another, its working or its lasting qualities may be quite different.

=The Vehicles.=--The vehicles by which the pigment is made fluent and
plastic are quite as important in their effects. They not only have to
do with the business of drying, owing to the substances used as
dryers, but they may have to do with the chemical action of one
pigment on another.

=The Preparation.=--Finally, the preparation of the pigment demands
the utmost skill and knowledge, if the colors are to be good. The
paints used by the old masters were few and simple, and the fact that
they prepared them themselves had much to do with the manner in which
they kept their color. The paints used now are less simple. We do not
prepare and grind them ourselves, and we could hardly do so if we
wished to, so we are the more dependent on the integrity of the
colorman who does it for us.

The preparation of the paint begins with the chemical or physical
preparation of each pigment, and then comes the mixing of several to
produce any particular color; and finally the mechanical process of
grinding with the proper vehicle to bring it to the proper fineness
and smoothness.

=Grinding.=--The color which the artist uses must be most evenly and
perfectly ground. The grinding which will do for ordinary house paints
will not do for the artist's colors. Neither will the chemical
processes suitable for the one serve fo