Developer is the strength. Here is how to pick it.
Developer is the peroxide you mix with color, toner or bleach. Its "volume" (10, 20, 30, 40) is how strong it is. With permanent color that decides how many levels the hair can lighten, how gently the cuticle opens and how much the scalp feels it. With bleach it decides the speed, and the lift is in the powder. The color tube decides the shade. The developer decides the lift.
| Volume | Peroxide | Lifts (with permanent color) | Use it for | Not for |
|---|---|---|---|---|
| 10 vol | 3% | none to half a level | Toners and demi-permanent glosses; Depositing color at the same level or darker | Lifting natural hair lighter |
| 20 vol | 6% | 1 to 2 levels | Permanent color, roots to ends; Gray coverage (the standard choice) | Three or more levels of lift |
| 30 vol | 9% | 2 to 3 levels | Lifting two or three levels with permanent color; Coarse, resistant hair that 20 vol will not move | Gray coverage (it lifts, and the white goes sheer) |
| 40 vol | 12% | 3 to 4 levels | High-lift blonde series on virgin hair, for the full four levels; Off-scalp bleach on coarse, healthy hair (brand permitting) | On-scalp bleach |
Lift figures are for permanent color on natural, uncolored hair. With bleach the developer sets the speed and the lift is in the powder, and nothing over 20 vol goes on the scalp with it.
Which developer do I need?
Answer four quick things and the tool names the volume. Same rules as the level chart.
Fine or fragile hair: drop one volume from the answer and add minutes rather than strength. Always strand test.
