Colored mortar joints may be produced in two ways, first, by the
use of a natural colored sand or ground granite or other stone, and
secondly, by the use of artificial mortar colors. Pure white joints
are obtained by using white sand or ground limestone or marble.
As the color of the mortar greatly affects the appearance of the
finished wall, much care should be given to the selection and
proper use of these colors, whether natural or artificial. As the
color of the finished mortar after it has set and dried is never
the same as that of the fresh mortar, experience is the only guide
for the proper preparation of the mortar. Someone has well said
that the right way to make mortar is to mix brains with it.
When artificial color is used, it should first be thoroughly mixed
with the dry sand. Never add this mixture to hot lime. But after
the slaked lime has thoroughly cooled, mix it with the colored
sand in batches in a separate box. If preferred, the color may be
made into a thick paste with water and then added directly to the
mortar. In either case, thorough mixing and uniform proportion of
quantities are essential. The more thorough the mixing and uniform
the proportions, the more permanent and uniform will be the color
and the less color required. Use the best colors obtainable on the
market, as cheap colors may ruin the appearance of the wall.
[Sidenote: Quantities]
As to quantity required, the exact amount of color varies greatly
with the exact shade of the color selected, the width of the mortar
joint, and the brand used. As a fair general estimate, it will take
approximately 75 pounds of coloring matter for every 1000 bricks
laid with 3/8 to 1/2-inch mortar joints. But it is always safest to
follow the directions of the manufacturer as to the kind of color
and the exact amount required.