SUMI Ink Practice Room

Today's character

boku · sumi
ink. Pine soot and glue, ground on a wet stone until it pools black.

Your handis the brush.

The sheet is dry and still. It stays that way until you move. How fast you go decides everything — the paper reads your speed as ink.

Slow floods a wet stroke that bleeds. Fast dry-drags into flying white. Press & hold to pool a bead. Trace the faint guide.

Speed
0px/s
Nib width
0px
Ink load
100%
Wetness
0%
Last mark
Waiting for your hand
Make a stroke and the studio will name it.
Draw here
This studio needs a live canvas.
Your browser could not open one, so the paper stays blank.

How the brush thinks

The mechanics

Nothing here is a recording. Every stroke is computed from your pointer in the moment — its velocity read frame by frame, then turned into width, wetness, and the way the bristles split. A real brush behaves like this because ink and paper are physical; the model just keeps the physics honest.

Slow · wet

Move gently and the bristles sit down and stay loaded. The stroke widens, and a soft halo wicks outward into the paper's fibres for a moment after you pass — the bleed you cannot rush.

Fast · dry

Whip the brush and it skims. Ink cannot keep up, so the tip narrows and the bristles separate into streaks with white paper showing through the gaps — the effect calligraphers call flying white.

Press · pool

Hold still with the button down and ink keeps flowing with nowhere to go. It pools into a dark, spreading bead and reloads the brush, so your next stroke starts wet again.

Run dry

A long stroke empties the brush. Ink load falls with distance, so the far end of a sweep goes thin and scratchy on its own — run out and even a slow hand goes dry. Press to load again.