A hair strand divided into 3 zones
A strand of hair is divided into 3 zones.
Hot zone: This zone starts from the scalp and 2-3cm out. The warm zone always lightens the most due to the heat from the scalp. This zone also attracts the warm pigments in the color the best.
Cold zone: Starts after the warm zone, i.e. from 2-3cm onwards in the hair. This zone lightens a little less. The cold zone attracts warm and cold pigments equally well.
Porous zone: Are lengths and ends that are dry in the hair. Hair that is very dry or damaged can contain large parts of this zone. This zone attracts the most cold pigments and more pigment as the hair shaft is more open. Porous zone can therefore turn blue/purple with overuse of silver shampoo.
It is the zones that can be the cause of uneven hair color. Tip: Colder color in the warm zone, warmer and lighter color in the cold zone for an even result.