Page 26 - HAIR COLOUR

To reform hair permanently you have to reform the alignment of the
Disulphide Bonds, this is done by a chemical process called permanent
waving. The hair is shampooed which opens the cuticle scales and breaks
down the salt and hydrogen bonds. While the hair is wet it is wound
around permanent wave curlers (rods). (Fig 21.)

Once the whole head is wound, permanent wave solution is applied to the
hair. The ammonia in the permanent wave solution opens the cuticle
scales still further allowing the permanent wave molecules to penetrate
deep into the protein structure breaking down about 30% of the
disulphide bonds.

The broken disulphide bonds are now capped with hydrogen molecules
from the perm lotion; this is what is known as the development stage.
The longer the hair is left in this stage the more disulphide bonds are
broken down, about 60% upwards would cause total disintegration, 40%
would cause serious over processing leaving the hair very dry and
damaged.

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