Developers have a pH of

• A. 1-2
• B. 2.5-4.5
• C. 6-7
• D. 8-9

Answer: (B)

Developers used in hair color are acidic to provide a controlled oxidation environment. The typical pH is around 2.5 to 4.5. In this range, hydrogen peroxide is stabilized, allowing it to oxidize dye precursors at a predictable rate so pigment forms properly without overly rapid breakdown or damage. The lifting of the cuticle is mainly caused by alkaline agents in the dye mixture, while the developer keeps the oxidation process balanced. If the pH were neutral or alkaline, peroxide would decompose more quickly and color development could be uneven or damaging. If it were extremely acidic, the solution would be too harsh and unstable for safe use.