Which type of hair requires the least amount of processing when coloring?

The type of hair that requires the least amount of processing when coloring is straight hair. This is because straight hair typically has a smoother cuticle layer, allowing color to penetrate more easily and uniformly. The structure of straight hair tends to absorb color effectively, leading to more predictable results with less time or product needed for processing.

In comparison, curly hair often has a more textured structure with tighter cuticle layers, which can make it more resistant to color absorption. Wavy hair, while somewhat easier to color than curly hair, still presents challenges due to its variable texture and potential for uneven processing. Coarse hair may also require more processing time and product, as the thicker cuticle can hinder color penetration.

Therefore, straightforward hair dynamics and structure support the conclusion that straight hair requires less processing for effective coloring, making it the best choice in this context.