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 | Demi toners and demi glosses; Depositing color at the same level or darker; Fragile, porous or previously lightened hair | Lifting natural hair lighter |
| 20 vol | 6% | 1 to 2 levels | Permanent color, roots to ends; Gray coverage (the standard choice); T18 type liquid toners | 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; Off-scalp bleach in foils | 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, virgin hair, where the brand allows it | 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. The developer volume chart has all four with percentages, lift and minutes in one table.
Which developer do I need?
Answer four quick things and the tool names the volume. Same rules as the hair level finder.
Fine or fragile hair takes color faster: keep the volume the job needs, take the first look earlier, and do not add minutes. With lightener, stay at 20 vol or lower on the scalp.
