A method of thickening and styling human keratinous fibres using a particular catalytic system

Combination (C1) of an aromatic compound with at least two adjacent hydroxy groups and a catalyst comprising a divalent manganese and/or zinc oxide or salt and an alkali(ne earth) metal bicarbonate is used to produce a composition for increasing the density of human hair and/or treating androgenic alopecia or for hair styling. Independent claims are also included for: (1) use of a combination (C2) as defined for C1 in which the molar ratio of manganese and/or zinc to bicarbonate is no more than 1:1 in a topical composition as an agent for increasing the density of human keratinic fibers or for hair styling; (2) cosmetic method for increasing the density of human hair or for hair styling, comprising applying a composition comprising C2 to the hair and/or scalp; (3) composition for care of human keratinic fibers and/or the skin from which they emerge, comprising C2 in a physiologically acceptable medium.