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CALCIUM SULFIDE.

Avoid CAS 20548-54-3 / DEPILATORY

A potent alkaline inorganic compound primarily utilized for its intense keratolytic and antimicrobial properties. In precision skincare, it is historically recognized for its ability to address severe blemish-prone skin and as a primary agent in chemical hair removal.

depilatory cosmetic biocide keratolytic

Science

Upon topical contact, the compound reacts with moisture and keratinocyte cysteine to liberate hydrogen sulfide. This process breaks disulfide bonds within hair and skin proteins, facilitating rapid exfoliation or depilation while simultaneously denaturing fungal and bacterial enzymes to provide biocidal benefits.


Research

Medium confidence
Effective range 1–6%
Optimal

5%

Key findings

  1. 01 Vleminckx's solution (sulfurated lime) demonstrated significant reduction in moderate-to-severe inflammatory acne lesions within a 14-day period.
  2. 02 Effective as a short-course treatment for parasitic skin infections at concentrations up to 10%.

Transparency

Not commonly dusted
Min. effective
1%
Red flag below
0.5%

Because it is highly reactive and has a distinct odor, it is rarely 'dusted' at low levels for marketing; it is typically used at functional concentrations or omitted entirely due to stability challenges.


The Formula

Solubility
Water
Optimal pH 10.8 – 12.7
0 7 14

Stability

Extremely sensitive to moisture and air; it hydrolyzes to produce toxic hydrogen sulfide gas. Requires a highly alkaline environment and inert packaging to remain stable.

Synergies

  • Alkaline bases
  • Inert carriers

Conflicts

  • Acids
  • Oxidizing agents
  • Metal salts
  • Nitrates

Safety

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

The EU SCCS limits concentrations to 6% as sulfur in alkaline earth sulfides. Due to the high pH required for stability, it poses a significant risk of chemical burns if misformulated.


Your Skin

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

Our Assessment

Avoid

While effective for targeted clinical conditions, its extreme alkalinity and potential for toxic gas liberation make it unsuitable for modern, high-precision daily skincare.


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