The most common reducing agent used in thio-free waves is which chemical?

• A. Cysteamine
• B. Mercaptamine
• C. Sodium thioglycolate
• D. Hydrogen peroxide

Answer: (A)

In thio-free waves, the reducing agent must break the hair's disulfide bonds so the strands can be reformed into a new shape. The most common reducing agent used for this purpose is cysteamine, an amino thiol that effectively reduces those bonds and is formulated specifically for thio-free products. Hydrogen peroxide is the neutralizer that oxidizes the cysteamine back to disulfide bonds after the hair has been reshaped. Sodium thioglycolate is used in traditional thioglycolate-based perms, not in thio-free formulas. Mercaptamine is another name you may see for cysteamine in some contexts, but cysteamine is the standard term in thio-free wave products.