Hair Colouring

Permanent hair color generally contains ammonia and must be mixed with a developer or oxidizing agent in order to permanently change hair color. Ammonia is used in permanent hair color to open the cuticle layer so that the developer and colorants together can penetrate into the cortex.

To achieve a permanent color, many hair dyes work using a system of ammonia (or ethanolamines in the case of some ammonia-free products), hydrogen peroxide, and p-phenylenediamine. The ammonia pulls apart layers of the hair's proteins, so that the dye can access the hair shaft.