Choosing the right developer: 3, 6, 9, and 12% simply explained

Whether for grey coverage, tone-on-tone, or significant lightening – the result of any coloration depends not only on the dye, but also on the developer. Its percentage determines how strongly it works. Here you can find out which strength is intended for what purpose.

What the developer actually does

The developer (also called oxidant) opens the hair's cuticle and activates the color or bleaching pigments. The higher the percentage, the more natural pigment is lightened. The specifications in percent and "Vol." (Volume) mean the same thing: 3% = 10 Vol., 6% = 20 Vol., 9% = 30 Vol., 12% = 40 Vol.

3% (10 Vol.) – Tone-on-tone and darkening

The mildest level. It hardly lightens at all and is suitable for tone-on-tone results, for darkening, or for refreshing color – gentle, because it changes little in the natural pigment.

6% (20 Vol.) – Grey coverage and 1–2 levels lighter

The all-rounder. 6% reliably covers grey hair and lightens by about one to two levels – the most frequent choice for permanent hair color.

9% (30 Vol.) – Stronger lightening

For about three levels of lightening or light shades. 9% works more powerfully and is often used with lightening colors and highlights. Here, it is worth taking a close look at the processing time and the condition of the hair.

12% (40 Vol.) – Maximum lightening

The strongest level, usually in combination with bleach. 12% lightens the most, but also places the most stress on the hair. Use only with experience, a strand test, and strict adherence to the manufacturer's instructions.

Mixing ratio and processing time

Color and developer are mixed differently depending on the product (often 1:1, for bleach 1:1.5 or 1:2). Always stick to the manufacturer's instructions, work with gloves, and perform a strand test beforehand. You can find the appropriate oxidant in Developer & Preparation.

Safety comes before a higher percentage

A stronger developer is not a shortcut to a better result. It can put more stress on the hair and scalp and should only be used if the specific color system explicitly provides for it. Developers from different brands or product lines should not be combined without the manufacturer's approval. In the case of an irritated scalp, severely damaged hair, or unclear prior treatment, a professional assessment is advisable.

Frequently asked questions about choosing a developer

Can I shorten the processing time with a higher percentage?

No. Percentage, mixing ratio, and processing time form a coordinated system. Deviations can unpredictably alter coverage, tone, and the condition of the hair.

Is 6 percent always right for grey coverage?

6 percent is common for many permanent color systems, but not universally applicable. The product instructions, desired tone, and starting hair remain the deciding factors.

At a glance

• 3% / 10 Vol.: Tone-on-tone, darkening
• 6% / 20 Vol.: Grey coverage, 1–2 levels lighter
• 9% / 30 Vol.: approx. 3 levels of lightening
• 12% / 40 Vol.: maximum lightening, especially with bleach

Do you want to dive deeper into lightening? Also read our guide on bleaching & lightening. Professional supplies and matching terms are available via the Dr.Kalla professional access.