Sumi ink

Sumi ink is a deep black ink traditionally made from soot and animal glue, historically ground from solid ink sticks with water on a stone but now widely sold pre-mixed in bottles for convenience. It is prized for its dense, matte black color and smooth flow, which makes it a popular choice for both East Asian brush calligraphy and Western pointed pen or broad edge lettering.

Compared to many dye-based calligraphy inks, sumi ink tends to sit more opaquely on the page and can shift slightly toward a warm or cool black depending on the brand, which some letterers use deliberately for tonal variation in a piece. It generally works well with both brush pens and dip pens, though very thick or old sumi ink may need thinning with water to flow through a fine pointed nib.

When choosing a sumi ink, check whether it is labeled fountain-pen safe if you plan to use it in a cartridge pen, since some traditional formulas contain particles that can clog fine mechanisms. A common mistake is leaving sumi ink capped for long periods without shaking or stirring, since pigment can settle and separate. Testing a small amount on your actual paper first avoids surprises with feathering or drying time.