Which type of dye is known for being semi-permanent and gentle on all hair types?

The type of dye known for being semi-permanent and gentle on all hair types is direct dye. These dyes do not require a developer or oxidation agent, which means they are less damaging and can easily coat the hair shaft. Direct dyes are formulated to adhere to the hair without altering the internal structure, allowing for vibrant color application without the harsh effects often associated with permanent dyes.

Direct dyes work by depositing color onto the outer layers of the hair rather than penetrating deeply into the hair cuticle. As a result, they tend to fade gradually with each wash, making them ideal for individuals looking for a temporary change without the commitment associated with more permanent coloring methods. Their gentle formulation makes them suitable for various hair types, including those that may be more delicate or prone to damage.

In contrast, oxidative dyes involve a chemical reaction that can change the hair structure permanently, which might not be suitable for all hair types. Temporary dyes, while also gentle, generally don't provide the lasting color effect associated with semi-permanent options. Permanent dyes offer long-lasting results but usually involve more significant processing that can lead to damage.