Sodium Hydrosulfite
What is Sodium Hydrosulfite?
Sodium hydrosulfite, chemically known as sodium dithionite (Na₂S₂O₄), is an inorganic compound produced synthetically as a white or yellowish powder. It serves primarily in hair care cosmetics, especially permanent waving and straightening products. This ingredient acts as a reducing agent by providing electrons to cleave disulfide linkages in hair's keratin proteins, enabling structural reshaping during chemical processing. Its reactivity allows hair fibers to adopt new configurations set by subsequent neutralizers. Beyond reduction, it functions as a viscosity controlling agent, modulating product thickness to enhance spreadability, stability, and user experience in creams or lotions. Employed mainly in rinse-off applications, it supports professional salon treatments and at-home kits, ensuring effective performance while minimizing residue.
Roles in Formulation
This ingredient serves the following purposes in cosmetic formulations:
Benefits
Facilitates hair reshaping in perming and straightening processes.
Maintains optimal product texture for even application.
Non-comedogenic, suitable for acne-prone users.
Who It's For
A quick guide for who this ingredient may suit (and who should be cautious).
| Who May Benefit | Who Should Avoid |
|---|---|
| Individuals pursuing chemical hair perms or waves. | People with sensitive or irritated scalps. |
| Users of professional hair straightening services. | Individuals prone to chemical sensitivities. |
| Those preferring stable, easy-to-apply hair treatments. | Those with open wounds on the scalp. |
Safety Notes
- Considered low hazard in cosmetic concentrations by safety assessments.
- Primarily used in rinse-off products to limit skin exposure.
Frequently Asked Questions about Sodium Hydrosulfite
What does sodium hydrosulfite do in hair products?
It breaks disulfide bonds in hair keratin for perming and controls viscosity for better texture.
Is it safe for cosmetic use?
Evaluated as low hazard when used as directed in rinse-off formulations.
Does it cause irritation or acne?
Low irritation potential in cosmetics; non-comedogenic with rating of zero.