Duration of the keratin straightening effect increases significantly depending on the number of the procedures you undergo. As reviews show, the repeated keratin procedures contribute to long-term retention of the effect. This is resulted from the keratin capability to be accumulated and to continue protecting hair over time.
Besides, the duration of the keratin layer effect depends on the hair length, hair shaft condition, hair washing frequency and types of hair-care products that are used. In most cases, research findings showed a positive relationship between retaining the effect and hair washing frequency. Nevertheless, it is also necessary to take into consideration the hair type.
To retain the keratin effect longer, you need to protect your hair from factors that destroy the protective layer, such as usage of sulfate shampoos within the first days after the procedure, sea water, sun, frequent hair washing and hair coloring. Therefore, you should dye your hair and go on vacation prior to keratin straightening.