The damage caused by peroxide developers varies depending on their strength (measured in volumes). Here’s a breakdown of the potential damage associated with each volume level, from 5 to 60 volume peroxide:

1. 5 Volume Peroxide (1.5%)

• Usage: Typically used for toning, deposit-only color, or semi-permanent color applications.
• Potential Damage: Very minimal. Since it doesn’t lift the hair’s cuticle much, the risk of damage is low. It may slightly open the cuticle to allow color molecules to deposit, but it won’t lighten or significantly alter the structure of the hair.

2. 10 Volume Peroxide (3%)

• Usage: Best for deposit-only color or subtle lift (up to 1 level), often used for semi-permanent or demi-permanent colors.
• Potential Damage: Minimal. It opens the cuticle slightly to allow pigment to penetrate, but it doesn’t cause much damage unless used repeatedly on fragile or over-processed hair.

3. 20 Volume Peroxide (6%)

• Usage: Most common for permanent hair color, capable of providing up to 2 levels of lift. It’s used for gray coverage or subtle lightening.
• Potential Damage: Moderate. At this level, the peroxide begins to break down the hair’s natural pigments more significantly, opening the cuticle and potentially causing some structural damage, especially on fine or already processed hair.

4. 30 Volume Peroxide (9%)

• Usage: Used for stronger lifting (up to 3 levels) and in high-lift color applications. It’s common in lightening darker hair.
• Potential Damage: Considerable. 30 volume opens the cuticle more aggressively and can cause damage, particularly if used on fragile or damaged hair. It breaks down the natural pigment more quickly, which can weaken the hair’s structure.

5. 40 Volume Peroxide (12%)

• Usage: Typically used for maximum lift (up to 4 levels) in high-lift tints or bleaching. It’s sometimes used with high-lift blonde formulations.
• Potential Damage: Significant. At this strength, the peroxide can cause a lot of damage, especially when left on too long or used improperly. Hair can become dry, brittle, and more prone to breakage.

6. 50 Volume Peroxide (15%)

• Usage: Rarely used in professional salons due to its high strength. It can lift hair very quickly (up to 5 levels) but is not recommended for most clients.
• Potential Damage: Very high. Hair is likely to become extremely damaged, dry, and break with improper use. At this level, the cuticle is significantly opened, and the natural pigments are aggressively broken down.

7. 60 Volume Peroxide (18%)

• Usage: Extremely high and uncommon for typical salon use. Usually reserved for extreme lifting on virgin hair in cases where very fast processing is needed.
• Potential Damage: Extreme. This level of peroxide can severely weaken the hair structure, leaving it highly prone to breakage and irreparable damage. Hair treated with 60 volume developer may require significant aftercare and even then may not recover fully.

Key Points on Damage:

• Higher Volume = More Damage: The higher the peroxide volume, the more it opens the cuticle and the more aggressive the lifting action, leading to more damage.
• Time and Frequency Matter: Even with lower-volume developers, repeated or prolonged use can lead to cumulative damage, especially when combined with heat or used on already fragile hair.
• Hair Type Sensitivity: Coarser hair may tolerate higher volumes better than fine or already damaged hair, but all hair types are susceptible to damage if over-processed.

In summary, while lower-volume developers tend to cause less damage, the higher the volume, the more caution is needed to protect the hair from over-processing and structural breakdown.