Ink, taken down the screen.

THE SYSTEM BEHIND THE SURFACE

Inside Pulled Ink.

What gets pulled is fire, and it moves the way fire moves because the motion comes from how buoyant flames behave. A pool fire sheds a vortex from its base at a steady rate and necks and bulges with it; that rate is f = 1.5/√D for a fire of width D (Cetegen & Ahmed, 1993), so every flame here keeps its own time and a narrow one flickers faster than a wide one. The gas accelerates as √z as it rises (McCaffrey), so a bulge reaches height z after 2√z/v₀ and its crests spread apart as they climb; above the flame tip only the shed puffs carry on, cooling as they go. That fire is then pulled: sampled at many points along the stroke and integrated, which carries its structure along the stroke — a flame stretches while its edges across the stroke stay sharp. A few columns are nicked and take their own offset along the stroke, either way, so the print tears into fine lines both darker and brighter than the ink around them. Grain is added after the pull, never through it.

Not a combustion model and not a print simulation. There is no chemistry, no radiation transport and no solved velocity field: the flames are placed and timed by those scaling laws, not evolved. There is no ink viscosity, no paper absorption, no screen mesh, no registration and no second colour pass. The pull is one straight direction applied uniformly, and the blade's nicks are a hash rather than a modelled edge.

7.209 ms GPU timestamp median; p95 7.93 ms. 1440x900 @ dpr 1.25; Metal driver on macOS Version 26.6.2 (Build 25G83); measured 2026-09-18. This is a recorded headless sample, not a browser FPS or mobile-performance guarantee.