What type of hair generally requires a stronger perm solution?

Coarse hair typically requires a stronger perm solution because of its thicker and more resilient structure. The cuticle layer of coarse hair tends to be more tightly packed, making it harder for the perm solution to penetrate and effectively alter the hair's internal structure. Using a stronger solution allows for better chemical processing that can overcome the natural resistance of coarse hair, ensuring that the desired curls or waves form properly.

On the other hand, fine hair might be more susceptible to damage from strong chemicals, requiring a gentler formulation. Dry hair often needs extra care and hydration rather than stronger chemicals, as the focus should be on restoring moisture and health rather than altering its structure aggressively. Colored hair, while it may be more delicate, does not necessarily mean a stronger solution is needed across the board; it often depends on the condition of the hair and the previous treatments it has undergone. Therefore, coarse hair stands out as the type that demands a stronger perm solution for effective curling.