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ALUMINUM HYDROXIDE.

Valuable CAS 21645-51-2 / HUMECTANT, OPACIFYING, SKIN CONDITIONING - EMOLLIENT, SKIN PROTECTING, VISCOSITY CONTROLLING

Aluminum Hydroxide is a versatile cosmetic ingredient, primarily acting as a physical shielding agent and texturizer. It effectively mattifies skin by absorbing excess sebum and stabilizes formulations.

viscosity controlling skin protecting opacifying humectant emollient

Science

It coats mineral filters like Titanium Dioxide, preventing the generation of reactive oxygen species. On the skin, it forms a thin film that absorbs oil, providing a mattifying effect, and acts as an amphoteric pH buffer.


Research

High confidence
Effective range 0.9–10.1%
Optimal

0.9%

Key findings

  1. 01 Effectively treats Titanium Dioxide in sunscreens to reduce photocatalytic activity.
  2. 02 Functions as a pigment stabilizer and opacifier in lipsticks with no systemic toxicity.
  3. 03 Maximum reported safe concentration for leave-on products, including eye area cosmetics.

Transparency

Not commonly dusted

The Formula

Solubility
Water
Optimal pH 5.5 – 8.5
0 7 14

Stability

As an amphoteric compound, it is most stable and least soluble in the near-neutral pH range (5.5-8.5). Extreme pH environments (<4 or >9) can compromise its structure or solubility.

Conflicts

  • Strong acids
  • Strong oxidizing agents
  • Aluminum-sensitive chelating agents

Safety

CIR Status
Safe as used
Max tested
10.1%
Sensitization risk Low

The CIR Expert Panel and SCCS confirm its safety in current cosmetic practices. It is chemically inert with limited skin penetration.


Your Skin

Yes Normal
Yes Dry
Yes Oily
Yes Sensitive
Irritancy Low
Comedogenicity Low

Our Assessment

Valuable

A valuable multi-functional ingredient, Aluminum Hydroxide enhances product stability, broadens applicability across skin types, and improves cosmetic elegance and performance.


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