Japanese Inks for Illustration

I have been looking at Japanese inks as used in Sumi-e illustration. They are produced in solid stick form and you have to grind them by hand shortly before you use them. There are two main types, blue and brown, although they both appear as black when used in concentrated form.

It is best to grind the ink using a special stone, shaped with a "land" area where you do the grinding, and a "sea" area to catch the ink as you grind it. It is best not to make the ink too long beforehand, as the particles start to settle out after a while and the ink becomes thin. I find the ink very good to work with, as it doesn't break up too much when you apply washes.