Composition and process for semi-permanent straightening of the hair

A process for semi-permanent hair straightening, comprising the following steps performed in this order:

• (a) application of a hair straightening composition;
• (b) leaving the composition on the hair for 10 to 60 minutes;
• (c) optionally rinsing off the hair;
• (d) drying the hair;
• (e) treating the hair with an iron having a surface temperature of 180±50° C., and
• (f) optionally rinsing off and/or shampooing the hair and drying,
• wherein the hair straightening composition has a pH of 1 to 3 and is an emulsion comprising:
• glyoxylic acid and/or a hydrate thereof and/or a salt thereof, at a total concentration in the range of 2.5 to 25% by weight, based on the weight of the total composition;
• at least one polymeric thickening agent having a viscosity of at least 500 mPa measured at a polymer concentration of 1% by weight, in water and at 20° C. with a Brookfield viscometer, wherein the polymeric thickening agent is an anionic polymer,
• a cationic surfactant;
• and
• at least one higher alcohol having 8 to 22 carbon atoms,
• wherein the combination with the application of a reducing composition or an alkaline relaxer is excluded.