Final answer:
Hair can typically be lifted 3 to 4 levels in one decolorization session without causing serious harm, but factors like hair health and product quality play a role. Professional assessment is crucial to prevent damage during this chemical process, especially when starting with dark brown or black hair.
Step-by-step explanation:
When decolorizing dark brown or black hair, the number of levels that hair can safely go through before experiencing serious harm varies depending on several factors such as hair health, strength, and the products used. Generally, it's possible to lift the hair 3 to 4 levels in one decolorization session without causing major damage. It is crucial to note that the lifting process must be done professionally to minimize the potential damage since the use of permanent hair coloring alters the hair's structure chemically.
During the decolorization process, the hair's natural color is removed, and synthetic color is added. The health of the hair, the quality of the hair products, and following the steps precisely, such as oxidizing the p-phenylenediamine to the quinonediimine, are all key factors for successful results without serious harm. For those with dark brown or black hair seeking significant lighting, it's often recommended to space the decolorization process over multiple sessions. This approach allows the hair's integrity to be maintained while gradually reaching the desired color level.