To produce fine qualities of coloured printing inks by mixing pure dry
colours with varnish, the printer will do well to give heed to the
following particulars:—
1. No more should be mixed at a time than will be required for the job in
hand.
2. Coloured inks should be mixed upon a slate or marble slab, by means of
the muller, and never upon an iron or other metallic table. The table,
before mixing, should be thoroughly clean, and perfectly free from the
slightest soil or trace of other inks.
3. For working coloured inks, the roller should not be too hard, and
should possess a biting, elastic face. When change of colour is required,
it should be cleaned with turpentine, and a moist sponge passed over the
face, allowing a few minutes for the roller to dry before resuming its
use.
For bronze printing, the roller should have a firm face, or the tenacity
of the preparation may destroy it; yet it must have sufficient
elasticity to deposit the preparation freely and cleanly on the type.