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BARIUM SULFIDE.

Questionable CAS 21109-95-5 / DEPILATORY

A potent alkaline earth sulfide primarily utilized as a fast-acting chemical depilatory in specialized grooming products. It is highly effective for thick or coarse hair removal but requires precise formulation control due to its high reactivity and alkaline nature.

depilatory reducing agent

Science

Barium sulfide functions by disrupting the structural integrity of hair. Upon contact with moisture, it generates hydrosulfide ions that penetrate the hair shaft, breaking the disulfide (cystine) bonds in keratin. This process, facilitated by a high pH environment that swells the hair, dissolves the protein structure into a soft mass that is easily wiped away from the skin surface.


Research

High confidence
Effective range 2–20%
Optimal

6%

Key findings

  1. 01 Demonstrated complete, painless removal of facial hair within a 15-20 minute application window.
  2. 02 Confirmed as an effective temporary solution for hirsutism, though clinical observation noted a significant risk of irritant contact dermatitis.

Transparency

Not commonly dusted
Min. effective
2%
Red flag below
1%

Because this is a functional active where effectiveness is tied to concentration, it is rarely 'dusted.' However, safety regulations strictly cap its usage; concentrations below 2% may fail to provide adequate depilatory action, while exceeding 6% (calculated as sulfur) violates international safety standards.


The Formula

Solubility
Water
Optimal pH 11 – 12.7
0 7 14

Stability

Decomposes in water to form barium hydroxide and hydrosulfide; must be protected from air and moisture to prevent premature degradation.

Synergies

  • Alkaline-stable thickeners
  • Emollients to mitigate irritation

Conflicts

  • Acids (creates toxic hydrogen sulfide gas)
  • Oxidizing agents
  • High thermal environments

Safety

CIR Status
Not reviewed
Max tested
6%
Pregnancy
Caution
Sensitization risk High

Regulated by the EU (Annex III/23) and Health Canada at a 6% sulfur-equivalent maximum. Ingestion or inhalation is highly toxic. Not recommended for use on broken or highly sensitive skin.


Your Skin

Yes Normal
No Dry
Yes Oily
No Sensitive
Irritancy High
Comedogenicity Low

Our Assessment

Questionable

While exceptionally effective for hair removal, its high irritancy potential and strict pH requirements make it less desirable than modern, gentler depilatories for precision skincare.


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