* Permanent dye works by depositing color, not lifting it. Permanent hair dye works by opening the hair cuticle, depositing color molecules, and then closing the cuticle. While it *does* contain some lifting agents (like ammonia or peroxide), these are primarily to create space for the new color molecules and are designed to lift virgin hair (hair that hasn't been dyed).
* Darker dye is already occupying the space in the hair shaft. The existing darker dye molecules are already in the hair shaft, blocking the lighter dye from taking hold properly.
* You'll likely just get a slight tint, or no visible change at all. At best, you might see a very subtle tint or tone shift in the darker color, but it won't be a noticeable lightening. The lighter dye might add some warmth or ashiness, depending on the specific colors involved.
* You risk damage. Applying more dye to already-dyed hair, especially if it contains peroxide, can cause damage, dryness, and breakage.
To go significantly lighter from dark dyed hair, you'll need to use a process that removes the existing color, such as:
* Bleach (Lightener): This is the most effective method for lightening dyed hair, but also the most damaging. It needs to be done carefully and ideally by a professional to avoid severe damage.
* Color Remover/Stripper: These products are designed to break down the artificial color molecules in the hair, allowing them to be washed away. They are generally less damaging than bleach, but may still dry out the hair. You may need to use several applications and/or bleach afterwards to reach your desired lightness.
* Gradual Fading: Repeated washing with clarifying shampoo and using anti-dandruff shampoo (which can have a fading effect) over time can help lighten the hair color gradually. This is the gentlest method, but also the slowest.
* Going to a Professional: If you want a dramatic change or are concerned about damaging your hair, the best option is to consult a professional hairstylist. They can assess your hair's condition and use the appropriate techniques to achieve your desired color while minimizing damage.
Important Considerations:
* Hair History: The number of times you've dyed your hair and the types of dyes used will affect how your hair responds to lightening processes.
* Hair Condition: Damaged or weak hair is more susceptible to breakage from lightening. You may need to deep condition and strengthen your hair before attempting any lightening procedures.
* Test Strand: Always do a test strand before applying any lightening product to your entire head. This will help you see how your hair will react and prevent any unwanted surprises.
In summary, putting lighter permanent hair dye over darker dye is not an effective way to lighten your hair. You'll need to use a color-removing process like bleaching or color stripping, or see a professional, to achieve significant lightening while minimizing damage.