Final answer:
Keratin-based chemical treatments smooth and straighten hair and typically last 2 to 6 months; maintenance and hair care practices can affect their longevity.
Step-by-step explanation:
Keratin treatments are a popular chemical process used to smooth and straighten hair. These treatments involve applying keratin and other chemicals to the hair, which work to alter its structure, resulting in a sleeker appearance. The results of a keratin treatment typically last between 2 to 6 months, depending on various factors such as the type of treatment, the individual's hair type, and how well they maintain it post-treatment. For example, using shampoos and conditioners that are free of sulfates and sodium chloride can help to prolong the effects. It is also important to note that the longevity of the treatment can be affected by the frequency of hair washing and the use of heat styling tools.
Keratin treatments are similar in nature to other chemical hair processes, such as perms and hair coloring. Perms change the hair's texture and shape through a chemical and sometimes thermal process, while hair coloring involves a chemical change in the hair's pigmentation. However, the term 'permanent' in hair treatments often refers to changes that last only until the hair grows out or is cut, not to an unchanging state.