The application describes a cosmetic method for the chemical treatment of keratinic fibers, in which i. a cosmetic composition is applied as a pretreatment agent to keratinic fibers, and ii. the keratinic fibers are subjected to a chemical treatment with an oxidizing agent and/or a reducing agent within a period of from about 5 seconds to about 24 hours after step i., wherein the cosmetic composition, based on its total weight, comprises from about 0.01 to about 4.00% by weight of a polyorganosiloxane of the formula (I) The damage to the keratinic fibers due to the oxidizing and/or reducing agents can be reduced by using the special pretreatment agent.