Final answer:
For extremely porous hair, a cosmetologist should use a color product with a lower developer volume to avoid damage and achieve a consistent color. Conditioning treatments before and after coloring can also aid in restoring the hair's health.
Step-by-step explanation:
If the hair is extremely porous, the cosmetologist should probably use a color product with a lower developer volume. Porosity refers to the hair's ability to absorb and hold moisture, and extremely porous hair can absorb color quickly and unevenly, leading to over-processing or damage. In such cases, using a color product with a lower volume of developer (e.g., 10 volume instead of 20 or 30) can prevent the hair from becoming too damaged. It is also beneficial to use products specifically designed for damaged or porous hair, which can help to equalize porosity and deliver a more consistent color result. Additionally, conditioning treatments can be used before and after coloring to help restore moisture and aid in the hair's overall condition.