Ink Chromatography — Forensic Document Ink Comparison

Questioned document examiners rarely rely on eyesight alone to tell two "black" or "blue" pens apart. Thin-layer chromatography separates each ink into its individual dye components by how strongly they partition between a moving solvent and a stationary silica plate, producing a reproducible fingerprint — the retardation factor, Rf — for every dye. This simulator develops two ink samples side by side in a real 3D developing chamber: the solvent front climbs the plate following the Lucas–Washburn √t law while each dye band separates out at its own Rf and spreads by diffusion, exactly as on a real TLC plate. Choose which ink runs in each lane, tune solvent polarity and plate temperature, and watch the live Rf readout and match/mismatch verdict reveal whether a signature was written in the same ink as the surrounding document — or added later with a different pen.