Hair dye

In detail

Permanent hair dye is not a pigment sitting on the hair; it is a small colourless precursor that penetrates the fibre and is then developed by an oxidiser into a large coloured molecule trapped inside. Everything difficult about a hair-dye spill follows from that. On a porous or protein surface the same chemistry runs, so the colour forms inside the material and cannot be lifted out by anything that would leave the material intact — which is why wool, silk, leather and unsealed stone are effectively unrecoverable. On a non-porous surface the outlook is far better, provided the splash is caught before the developing reaction finishes: a bathroom basin, a tiled floor or a laminate worktop wiped immediately usually clears completely, and the same splash left overnight often does not. The carpet institute routes hair dye through detergent, vinegar solution, warm water, a spot removal kit and then a professional, and the presence of the acidic step early is the tell — it is there to shift the alkalinity the developer left behind. Speed matters more here than the choice of product.

Why

• Hair dye is explained by Oxidation and bleaching
• Hair dye is explained by Dye migration and colour bleeding