Get a Free 5ml Mini Now Free 5ml Mini With Every Order of The Mantle

CALCIUM OXIDE.

Optional CAS 1305-78-8 / BUFFERING

A potent mineral alkaline agent used in precision skincare to regulate formulation pH and provide targeted antimicrobial benefits. Its high reactivity makes it an effective tool for keratin softening and deep-cleansing applications in specialized treatments.

pH Adjuster Buffering Agent Antimicrobial Absorbent Abrasive

Science

Calcium Oxide functions by creating a high-alkaline environment that disrupts microbial cell walls and generates secondary reactive oxygen species (ROS) for disinfection. At higher concentrations, it interacts with keratin proteins to soften the skin's surface, while its hygroscopic nature allows it to absorb excess moisture and sebum.


Research

Medium confidence
Effective range 0.2–16.5%
Optimal

0.2%

Key findings

  1. 01 Low-dose (0.2%) application significantly enhances wound healing and capillary formation in infected tissues without the irritation associated with higher concentrations.
  2. 02 Historical clinical data supports its use at higher percentages in Vleminckx's solution for keratolytic treatment of acne and skin congestion.

Transparency

Not commonly dusted
Min. effective
0.2%
Red flag below
5%

While often used as a minor pH adjuster, its clinical benefits for wound healing and antimicrobial activity are seen at concentrations as low as 0.2%. Using it above 5% in standard skincare is a red flag due to high alkalinity and potential for skin irritation.


The Formula

Solubility
Water
Optimal pH 11 – 12.8
0 7 14

Stability

Highly reactive and exothermic; it converts to calcium hydroxide upon contact with water. Must be kept in anhydrous, sealed environments to prevent 'air-slaking' into calcium carbonate via CO2 exposure.

Synergies

  • Sulfur
  • Magnesium Oxide

Conflicts

  • Acids
  • Water
  • Ethanol
  • Aluminum
  • High humidity

Safety

CIR Status
Safe as used (deferred to FDA)
Max tested
5%
Pregnancy
Safe
Sensitization risk Moderate

Classified as a Skin Irritant (Category 2) and Eye Damaging (Category 1). Safety is highly dependent on final product pH and concentration.


Your Skin

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

Our Assessment

Optional

A powerful alkaline tool that is excellent for niche antimicrobial or keratolytic needs but requires expert formulation to mitigate its high irritation potential.


Related

Finding similar ingredients…


References