What relaxer requires the application of a chemical neutralizing solution?

Acid relaxers work differently as they do not require a neutralizing solution. Instead, they use an acidic pH to break disulfide bonds in the hair. The process can be reversed through the application of a neutralizing shampoo, but it is not an essential step as it is with hydroxide relaxers.

Thio relaxers, or ammonium thioglycolate relaxers, do not necessitate a chemical neutralizing solution either. They are applied and then rinsed out, and a separate neutralizing agent is not required to stop the action of the thio relaxer. Instead, a neutralizer is often used to reform the disulfide bonds after styling.

Oxidizing relaxers typically refer to products that use peroxide or similar agents to lighten hair color rather than to relax curls. They do not need a neutralizing solution to stop their action since they serve a different purpose in hair treatment, primarily focusing on color rather than the chemical alteration of curl structure.