Here's a breakdown:
* What it will do:
* Slightly open the hair cuticle: Developer is primarily used to open the hair cuticle so that hair color or lightener can penetrate. Using it alone will still slightly open the cuticle.
* Very slight lifting: 20 volume developer contains hydrogen peroxide, which can lift the natural pigment of your hair, but only by a very subtle amount - usually around 1 level. The darker your hair, the less noticeable this will be.
* Potentially make hair feel drier: Opening the cuticle without depositing color or moisture can sometimes lead to a drier feel.
* Activate some bond builders: Some bond builders contain ingredients that are activated by peroxide. Using developer alone with these bond builders could potentially provide some strengthening benefits.
* What it won't do:
* Change your hair color significantly: Without hair dye or lightener to deposit color, you won't see a dramatic change.
* Cover grays: Developer alone will not cover gray hair.
* Lighten your hair significantly: The lifting power is very minimal.
* Why might someone use it alone?
* To refresh natural highlights: If you have naturally light pieces in your hair, a very diluted developer application might slightly enhance them without a full coloring process.
* As a pre-treatment: Some people believe that opening the cuticle with developer before applying a deep conditioner or hair mask can help the treatment penetrate better. However, opinions vary on the effectiveness of this.
* With a bond builder: As mentioned above, to activate certain bond-building treatments.
* Accidental mistake: Sometimes people mistakenly use developer alone thinking it will lighten their hair without color, but this is not effective.
* Important Considerations:
* Hair condition: If your hair is already dry, damaged, or porous, using developer alone might exacerbate these issues. Always do a strand test first.
* Strand test: Before applying developer to your entire head, perform a strand test to see how your hair reacts. This is crucial to avoid unwanted results or damage.
* Timing: Don't leave the developer on your hair for an extended period. Start with a shorter processing time (e.g., 10-20 minutes) and monitor the results.
* Rinse thoroughly: After processing, rinse your hair thoroughly with cool water and use a moisturizing conditioner or hair mask to help close the cuticle and restore moisture.
* Lower Volumes are Safer: If you are unsure, a lower volume like 10 volume developer would be a gentler alternative.
In summary, while you *can* use 20 volume creme developer alone, it's generally not recommended unless you have a very specific reason and understand the potential effects. It's crucial to consider your hair's condition and perform a strand test beforehand to avoid any unexpected or undesirable results. If you're aiming for a significant color change, you'll need to use it with hair dye or lightener.