Hair treatment method

A cosmetic hair treatment method comprising:

• a) applying a mechanical tension to the hair to be treated,
• b) exposing the hair under the mechanical tension to microwaves, while contacting the hair with a solvent vapour, without complete drying of the hair during the microwave exposure, to obtain the treated hair;
• wherein
• the solvent vapour is generated by evaporation of a solvent which is in contact with the hair to be treated before the exposure to the microwaves, the solvent vapour having, in the vicinity of and/or in contact with the hair, in step b), a temperature of between 100 and 150° C.;
• and
• after step b) the hair retains at least 5% of the weight of liquid compounds present before step b), in contact therewith, the liquid compound adding to natural moisture of the hair before treatment,
• and wherein a frequency of the microwaves is between 500 MHz and 10 GHz,
• the method further comprising c) applying to the treated hair at least one composition for durable shaping of the hair, the composition being a reducing composition comprising one or more reducing agents, the pH of the reducing composition being between 7 and 11, the reducing composition comprising at least one alkalifying agent, the alkalifying agent being selected from:
• aqueous ammonia,
• alkanolamines and derivatives thereof,
• ethoxylated and/or propoxylated ethylenediamines,
• alkali metal silicates,
• amino acids,
• compounds of formula (II):
• wherein
• W is a propylene residue which is optionally substituted by a hydroxyl group, or a C1-C4 alkyl radical, and
• Ra, Rb, Rc and Rd are identical or different and may be a hydrogen atom or a C1-C4 alkyl or C1-C4 hydroxyalkyl radical.