Patent ID: 8840684

Claim:
A process for dyeing keratin fibers, comprising: applying to the fibers at least one cationic direct dye chosen from cationic direct dyes comprising a disulfide function and cationic direct dyes of formula (I) comprising a protected thiol function: A-(X) p —C sat —S—U (I) and organic acid salts, mineral acid salts, optical isomers, geometric isomers, tautomers and solvates thereof, wherein in formula (I): U is a radical chosen from —S —C′ sat —(X′) p′ -A′; A and A′, which may be identical or different, are radicals comprising at least one cationic chromophore; X and X′, which may be identical or different, are chosen from linear and branched, saturated and unsaturated divalent C 1 -C 30 hydrocarbon-based chains, optionally interrupted and optionally terminated at at least one end with at least one divalent group chosen from —N(R)—, —N + (R)(R)—, —O—, —S—, —CO—, and —SO 2 — wherein R, which may be identical or different, is chosen from hydrogen C 1 -C 4 alkyl radicals, hydroxyalkyl radicals, and aminoalkyl radicals; and aromatic and non-aromatic, saturated and unsaturated, fused and non-fused (hetero)cyclic radicals optionally comprising at least one identical or different, optionally substituted heteroatom; p and p′, which may be identical or different, are chosen from 0 and 1; C sat and C′ sat , which may be identical or different, are chosen from optionally cyclic, optionally substituted linear and branched C 1 -C 18 alkylene chains; and applying water vapor to the fibers; wherein the at least one cationic direct dye and the water vapor may be applied together or separately.