Here's why developer is needed for permanent hair color:
* Lifting: Developer (hydrogen peroxide) is what lifts your natural pigment to allow the color to deposit and change your hair color.
* Color Development: The developer mixes with the color molecules, allowing them to penetrate the hair shaft and deposit the new color.
If you use a permanent hair color without developer, the color will not take, and your hair will not change color.
However, semi-permanent and temporary hair dyes deposit color directly onto the hair shaft without lifting the natural pigment. This means they don't require a developer.
Always follow the instructions on your specific hair dye product.