sepia inks
Inks that are compounded from the dark pigment
discharged by the common cuttle-fish and other
cephalopods, family Sepiidae, in order to mask
retreat. The effect of this fluid is somewhat
remarkable, in that 1 part ink in 1,000 parts of
water is sufficient to make the latter opaque. It
was used as an ink in ancient Rome, but is little
used today except as an artist's coloring. The
dried ink is pulverized and boiled with alkali,
which is subsequently neutralized with acid so as
to precipitate the pigment. The pigment is then
washed, dried, and incorporated with oil. The main
feature of this process, with regard to
permanency, is the amount of acid used to
precipitate the pigment, because acid in ink is as
detrimental to paper, as is acid in the paper
itself. Although sepia inks are reasonably
permanent in dull light, they tend to fade rapidly
when exposed to bright natural light. (20 , 143 )
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