Printers' inks consisting solely of purified lampblack and vehicle give, of course, impressions which are pure black. It is, however, well known that a black which has to a practiced eye a tinge of blue in it looks much better than a pure black. To make such an ink many makers mix the lampblack with a blue pigment, which is added in very fine powder before the first grinding. Prussian blue is the pigment usually chosen and gives very attractive results. Prussian blue is, however, not a remarkable stable substance, and is very apt to turn brown from the formation of ferric oxide. Hence an ink made with Prussian blue, although it may look very fine at first, often assumes a dull brown hue in the course of time. Excellent substitutes for Prussian blue are to be found in the Induline blues. These are very fast dyes, and inks tinted with them do not change color. As pure indigo is now made artificially and sold at a reasonable price, this extremely fast dye can also be used for tinting inks made with purified lampblack.

To Give Dark Inks a Bronze or Changeable Hue

Dissolve 1.5 pounds gum shellac in 1 gallon 65 per cent alcohol or cologne spirits for 24 hours. Then add 14 ounces aniline red. Let it stand a few hours longer, when it will be ready for use. Add this to good blue, black, or other dark ink, as needed in quantities to suit, when if carefully done they will be found to have a rich bronze or changeable hue.

Quick Dryer for Inks Used on Bookbinders' Cases

Beeswax, 1 ounce; gum arabic (dissolved in sufficient acetic acid to make a thin mucilage), J ounce; brown japan, 1/4 ounce. Incorporate with 1 pound of good cut ink.