Compared with a thiol-based (ammonium thioglycolate) perm, a sulfite-based 'true acid' perm typically:
a.Requires no neutralizer because no bonds are broken
b.Uses sodium hydroxide as its reducing agent
c.Has a higher pH and processes faster than thio waves
d.Has a near-neutral to slightly acidic pH and produces a softer, less aggressive curl
Explanation
Sulfite (acid) waves use ammonium sulfite or bisulfite at a pH near 6.5 to 7. They swell the hair less than alkaline thio waves, so they create a softer curl and are gentler on porous or color-treated hair, though processing time is longer.
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