Science
Mechanism of Action
Potassium Thioglycolate operates by chemically cleaving the disulfide bonds within keratin, the foundational protein of hair. This weakens the hair's structure, allowing it to be easily removed (in depilatories) or reshaped (in waving/straightening products). The process is significantly enhanced by alkaline agents that maintain the optimal pH for the reaction. While effective on hair, its highly alkaline nature can also denature stratum corneum proteins and disrupt skin lipids, potentially contributing to irritation.
Research
Clinical Evidence
High confidenceN/A
Key findings
- 01 Deemed safe for use in depilatories when formulated to be non-irritating and used as directed, within a pH range of 7 to 12.7 (CIR Expert Panel, SCCS).
- 02 Considered safe for general use in hair waving or straightening products, with a pH of 7 to 9.5 (SCCS, EU Cosmetics Regulation).
- 03 Safe for professional use in hair waving or straightening products (pH 7-9.5) and professional eyelash waving products (SCCS, EU Cosmetics Regulation).
- 04 Safe for use in hair rinse-off products, maintaining a pH up to 9.5 (SCCS, EU Cosmetics Regulation).
- 05 Safe for use in hair straighteners, permanent waves, tonics, dressings, wave sets, other non-coloring hair products, and hair dyes and colors (CIR Expert Panel).
Transparency
Dusting Analysis
Potassium Thioglycolate's primary mechanism involves the chemical alteration of hair proteins, and it operates at pH levels that can be disruptive to skin. It is not typically 'dusted' into general skincare formulations for ancillary benefits due to its specific action and potential for irritation.
The Formula
Formulation
Stability
Potassium Thioglycolate is highly susceptible to oxidation, necessitating protection from heat above 40°C (30°C is preferred) and air exposure. The use of high-purity water is critical to prevent discoloration caused by metal ions. Formulations should be stored in cool, dry conditions, completely shielded from sunlight, heat, and air. Recommended packaging includes glass or polyethylene (PE) plastic. All raw materials, such as emulsifiers and emollients, must exhibit stability under highly alkaline conditions (pH 12-12.5).
Conflicts
- strong oxidizing agents
- metal charges in water
- heat above 40°C
- air exposure
- raw materials unstable in alkaline conditions
Safety
Safety Profile
The CIR Expert Panel concluded Potassium Thioglycolate is safe for use in various hair products (straighteners, permanent waves, styling products, dyes) up to 15.2% (as Thioglycolic Acid). It is also safe for depilatories if formulated to be non-irritating under recommended use conditions, with precautions for minimizing skin exposure for both hairdressers and consumers. The SCCS found it safe for depilatories up to 5% (pH 7-12.7), hair rinse-off products up to 2% (pH up to 9.5), and professional eyelash waving up to 11% (as thioglycolic acid). However, self-application for eyelash waving by consumers is not advised due to significant eye irritation risk.
Your Skin
Skin Compatibility
Our Assessment
Verdict
While effective in specific hair treatment applications, Potassium Thioglycolate's high irritancy potential and ability to disrupt skin proteins and lipids make it unsuitable for general precision skincare formulations focused on promoting skin health.
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References
Sources