A method of combatting colour loss from a dyed material, the method comprising contacting the material with a composition comprising a compound of formula (I): Wherein R is an optionally substituted hydrocarbyl group having at least 5 carbon atoms, and R1 is a hydrogen or a solubilising group is provided. The material may be a keratinous material such as hair or a textile material such as wool. R may be phenyl or CH3(CH2)n wherein n is from 4 to 10. The composition may contain surfactants, an alpha-substituted aldehyde and/ or a hydroxyl aldehyde, a polycarboxylic acid derived chelating agent and a crosslinking agent comprising two or more maleic acid derived reactive moieties with a linker having two or more amino groups. A hair care composition comprising a compound of formula (I) is provided. A method of colouring hair comprising (a) contacting the hair with a colouring composition； and (b) contacting the hair with a composition comprising a compound of formula (I) is outlined.L'invention concerne un procédé de lutte contre la perte de couleur à partir d'un matériau coloré, le procédé comprenant la mise en contact du matériau avec une composition comprenant un composé de formule (I) : (I) dans laquelle R est un groupe hydrocarbyle éventuellement substitué ayant au moins 5 atomes de carbone, et R est hydrogène ou un groupe de solubilisation.
