Answer:
Hydroxide Relaxers
The hydroxide ion is the active ingredient in all hydroxide relaxers, which
are very strong alkalis with a pH over 13. Sodium hydroxide, potassium
hydroxide, lithium hydroxide, and guanidine hydroxide are all types of
hydroxide relaxers, which can swell the hair up to twice its normal diameter.
Hydroxide relaxers are not compatible with thio relaxers, permanent waving,
or soft curl perms because they use a different chemistry. Thio relaxers use
thio to break the disulfide bonds. The high pH of a thio relaxer is needed
to swell the hair, but it is the thio that breaks the disulfide bonds.
Hydroxide relaxers have a pH that is so high that the alkalinity alone
breaks the disulfide bonds. The average pH of the hair is 5.0, and many
hydroxide relaxers have a pH over 13.0. Since each step in the pH scale
represents a tenfold change in concentration, a pH of 13.0 is 100 million
(100,000,000) times more alkaline than a pH of 5.0 (Figure 20–45).
Hydroxide relaxers break disulfide bonds differently than in the
reduction reaction of thio relaxers. In lanthionization (lan-thee-ohny-ZAY-shun), the process by which hydroxide relaxers permanently
straighten hair, the relaxers remove a sulfur atom from a disulfide bond
and convert it into a lanthionine bond. A disulfide bond consists of two
bonded sulfur atoms. Lanthionine bonds contain only one sulfur atom.
The disulfide bonds that are broken by hydroxide relaxers are broken
permanently and can never be re-formed. That is why hair that has been
treated with a hydroxide relaxer is unfit for permanent waving and will
not hold a curl.
Explanation:
