Which relaxer is known for its mildness and low pH and is compatible with thio relaxers?

The ammonium bisulfite relaxer stands out due to its mildness and low pH level, making it a suitable choice for clients with fragile hair and sensitive scalps. This relaxer operates in a gentler manner compared to more alkaline options, which can cause significant structural changes to the hair. Its compatibility with thio relaxers adds to its appeal, as it allows for a range of chemical services without the risk of negatively interacting with each other, thus providing versatility in hair treatments.

In contrast, ammonium thioglycolate relaxers are typically stronger and more alkaline, making them less suitable for delicate hair types. Potassium hydroxide relaxers are more aggressive in their chemical action and can lead to damage if not used properly. Glyceryl mono-thioglycolate is also effective but may not be as mild or widely compatible as ammonium bisulfite. Therefore, the ammonium bisulfite relaxer's intrinsic characteristics of being mild and low pH highlight its effectiveness and safety for specific applications, particularly in combination with thio relaxers.