Final answer:
Brushing the hair before a scalp treatment helps remove all, except hair color.
Step-by-step explanation:
Brushing the hair before a scalp treatment helps remove all of the following EXCEPT hair color. Dirt, dead skin cells, and natural oils can be removed from the hair and scalp by brushing. Hair color, on the other hand, is not affected by brushing and remains intact. Brushing helps to distribute the natural oils produced by the scalp throughout the hair, promote blood circulation in the scalp, and remove any loose debris from the hair and scalp.