Vermilion, the color for ex-libris ownership stamps,
has been used extensively in both China and Japan for centuries. The
reason for this is that "vermilion ink" has long been considered
the counterpart of black "India ink." This vivid color also
presented a strong contrast with the black used for printing, calligraphy,
and drawing. Unlike blue or green, there was no fear of it fading or
changing color with age.
Vermilion has long been considered a royal color in China. As it did
not fade or vary in shade over time, it was held to be unchanging like
gold, making it an auspicious color sought after by people seeking perpetual
youth and long life. And so it was used as a pigment for ink pads. It
is well known that vermilion was expensive and has been highly valued
in Japan since ancient times. As vermilion was being used in a culturally
advanced country like China at that time, it seems natural that the
people of Japan would follow suit.
Ex-libris ownership stamps use vermilion ink pads as their source
of color. The formula for these can be seen in "Wakan Sansai
Zue" (encyclopaedia) edited by Ryoan Terajima, and "Mojuno
no Kusaguki" by Nanpo Ota. There are slight variations in these
materials, but the basically accepted method is to grind cinnabar into
a powder, then add some oil, such as castor oil, little by little, while
mixing thoroughly. Following that, wormwood was carefully chopped to
produce a cotton-like texture and then added to the mixture. Alternatively
sesame oil was used.
A list of formulas used in China can be found in "Ju-jia Bi-yao Shi-lei
Guan-ji" written by an unknown author during the Yuan dynasty. In China,
the upper classes used an ink pad made by adding precious stones, gold leaf, pearls,
coral, agate, or isinglass to give it an iridescent color.