This article is from the Miniatures Painting FAQ, by Brenda Klein firstname.lastname@example.org with numerous contributions by others.
Inks are just that, semi-transparent tones that can be used to add
colour and shading to a miniature. If you wish to go beyond the
range of paints, you might wish to try working with them.
Unless using for outlining, inks should always be thinned
slightly for glazing and rather a lot for washing. A milk-like
consistency is best for washing (or even thinner, since you can
always wash again if more is needed) and about 50-50 ink and water
is best for glazing.
If you do not get the specially formulated for miniatures inks
(the only brand known to the author is Citadel, and they're very
good), then the best information available comes from Wade
Hutchison (email@example.com), as posted to rec.games.
miniatures and is edited and used here without permission:
"A tip about Inks. If you go to the art supply store to buy
your inks, be sure and get "pigmented" inks, not transparent
ones. Pigmented inks, especially brown, work much better for
a wash than the transparent ones. Red and blue don't seem to
matter as much. For shading white, there is a really good ink
color called "Payne's Grey" whick is a kind of blue-grey. It
does a much better job than black when washing white or very
light tans and greys."
Recommended also have been Windsor & Newton inks.
Inks are best used as washes, for outlining, and as glazes.
When washing with inks on a matt surface (or on any other,
actually), a gentle blowing of air from the top to the bottom
of the miniature helps keep the ink from drying back up into the
raised areas. The author usually blows lightly until the wash
stops looking slick-wet.
% Glazing is done with inks. In this technique, a slightly darker
tone than the base is thinned and then brushed over the entire
surface and allowed to dry. Glazing brings out a richness of
colour not possible with paint alone. Glazing should be done
after highlighting and shading and tends to bring up detail of