The General Recommendation:
* 20 Volume Developer: This is generally the *safest* and *most recommended* choice for covering grey hair. It provides adequate lift to open the hair cuticle and deposit the color effectively without causing excessive damage or brassiness.
Why 20 Volume is Usually Preferred:
* Sufficient Lift: 20 volume lifts the hair enough to allow the color to penetrate the grey hair cuticle. Grey hair can be resistant to color, so some lift is necessary.
* Less Damage: 20 volume is gentler on the hair than 30 volume. Grey hair is often finer and more fragile, making it more prone to damage.
* Better Coverage: Slower processing time allows the color molecules to fully penetrate and adhere to the hair shaft, ensuring complete and even grey coverage.
* Reduced Fading: Less cuticle damage means the color is sealed in better, leading to less fading over time.
When 30 Volume *Might* Be Considered (With Caution):
* Extremely Resistant Grey: If you have a very high percentage of grey hair (80% or more) and find that 20 volume consistently fails to provide adequate coverage, *only then* might you consider 30 volume.
* Very Dark Hair: If you are significantly lightening your hair (2 or more levels), you might need a higher volume developer to achieve the desired lift, *but it's still best to use a lower volume for the roots and the resistant grey hair first.*
* Thick, Coarse Hair: Sometimes very thick, coarse hair can be more resistant to color, but again, proceed with extreme caution.
* Experienced Colorist: Using 30 volume is best left to experienced colorists who can assess your hair and formulate the color correctly to minimize damage and brassiness.
Important Considerations When Using 30 Volume:
* Monitor Closely: Watch the hair carefully during processing. Check for lift and coverage frequently.
* Short Processing Time: Don't over-process. 30 volume works faster, so a shorter processing time is usually required.
* Risk of Damage: Be aware that 30 volume can cause dryness, breakage, and fading if used incorrectly.
* Potential for Brassiness: A higher volume developer can expose underlying warm tones, leading to a brassy or orange result, especially on darker hair.
* Strand Test: Always perform a strand test before applying the color to your entire head. This will help you determine if the color and developer strength are right for your hair.
Recommendations:
1. Start with 20 Volume: Unless you have a specific reason to use 30 volume, begin with 20 volume.
2. Consult a Professional: If you're unsure or have had trouble covering your grey hair in the past, consult a professional hair colorist. They can assess your hair type, grey percentage, and color goals to recommend the best approach.
3. Use a Grey Coverage Specific Formula: Many hair color brands offer lines specifically designed for grey coverage. These formulas are often formulated with more pigment to effectively cover grey hair.
4. Consider a "Double Process": For very resistant grey, a colorist might recommend a "double process" where they pre-soften the grey hair with a separate product *before* applying the color. This helps the color adhere better.
In summary, 20 volume is the best default choice for covering grey hair for most people. 30 volume should only be considered in specific circumstances and with caution. Always prioritize the health of your hair and, when in doubt, consult a professional.