Patent ID: 6923953

Claim:
Method for fixing a sunscreen or shine agent on hair keratin fibres comprising the stops of reducing the disulphide bonds of the hair keratin with an aqueous reducing agent solution consisting of (1) phosphines or a salt thereof and a mineral or organic acid, wherein the pH of the (1) phosphines solution is in the range 2 to 10 or (2) thiols, wherein the pH of the thiols solution is in the range 6.5 to 9 by using a polyquaternary ammonium hydroxide said reducing agent generating reactive sites only on the surface of said keratin fibres to a depth of less than 10 μm and of covalently fixing on said reactive sites at least one sunscreen or shine agent said sunscreen or shine agent containing at least one reactive function being capable of reacting with said reactive sites formed on the surface of the keratin fibres.