Thio Relaxers
Thio relaxers and perms use ammonium thioglycolate (ATG); the straightening products are usually at a much higher pH and concentration than perm lotions.
These relaxers are also thicker with higher viscosity or thickness, which makes for an easier relaxer application.
Thio relaxers and perms break the disulphide bonds in hair, like the permanent waving process. When enough of the disulphide bonds are broken, the relaxer is rinsed from the hair, and the hair is towel dried. After towel drying, a neutraliser of some sort is applied to the hair.
Ammonium thioglycolate is also known as perm salt for its use in permanent waves. Perm salt is a chemical reducing agent which selectively weakens the hair’s disulphide bonds instead of disrupting the entire protein but strips out the natural oils even more thoroughly than the alkali hydroxide products. Afterwards, the thioglycolate must be oxidised with a usually with a solution of hydrogen peroxide