Here's why:
* Darker dyes deposit color: Darker hair dyes work by depositing color onto your hair shaft. They don't need to remove any existing pigment, they simply add more.
* Bleach removes color: Bleach is used to lighten hair by removing natural pigment. If you're going darker, you don't need to remove any pigment.
* Damaging: Bleach is damaging to the hair. It can weaken the hair shaft, leading to breakage, dryness, and split ends. There is no need to risk this damage when going darker.
* Exceptions: In some cases, if your hair is very light (e.g., platinum blonde) or has been previously lightened/bleached, it might be necessary to "fill" the hair with a color that mimics some of the underlying tones that were removed during the bleaching process. Without this step, the dark color may appear muddy, fade quickly, or have a green or grey tinge.
Important Considerations:
* Previously dyed hair: If you have previously dyed your hair with a lighter color, the darker dye may react differently to the previously dyed areas than it does to your natural hair. In these cases, a consultation with a professional stylist is highly recommended to ensure even color distribution.
* Greenish tint after bleaching: If you've bleached your hair and you're trying to go darker, you might notice a greenish tint. You'll need to use a red or orange based product to counteract this before applying your target shade.
In summary: You almost never need to bleach when going darker. Focus on choosing the right shade of dye and following the instructions carefully to achieve your desired result. Consider consulting a professional stylist for the best results, especially if your hair has been previously treated or if you're making a significant color change.