Magnesium Stearate

What is it? Magnesium Stearate is the salt of magnesium and stearic acid.
INCI Magnesium Stearate
Appearance Fine white powder
Usage rate Typically 5–10% for loose powders. For creamy cosmetics and binding powders for pressing you’ll need to use it at higher rates.
Texture Magnesium Stearate is surprisingly creamy when handled—it has a wonderful, rich slip when rubbed between the fingers.
Scent Nothing much—perhaps a bit “fatty”
Approximate Melting Point 130°C (266°F)
Solubility Oil, warm alcohol
Why do we use it in formulations? Magnesium Stearate gives our colour cosmetics both slip and adhesion. It is also used as a binding ingredient when pressing powders.
Do you need it? Magnesium Stearate is essential if you are making your own makeup.
Refined or unrefined? Magnesium Stearate only exists as a refined product.
Strengths Excellent, inexpensive ingredient for increasing slip and adhesion/wear time in colour cosmetics.
Weaknesses I can’t think of any!
Alternatives & Substitutions You could try zinc stearate or magnesium myristate, but you will need to re-test the formula for performance and wear time. I do not recommend eliminating this ingredient as both slip and adhesion are crucial to the success of colour cosmetics.
How to Work with It Blend it in with the other powders in powdered cosmetics. In cream cosmetics it can be melted into the oil phase, but I’ve also found if that it incorporates well if pre-ground with the other powders and stirred into the creamy base.
Storage & Shelf Life Stored somewhere cool, dark, and dry, magnesium stearate should last at least two years.
Tips, Tricks, and Quirks Stearic acid is almost always vegetable derived, but it is possible to source it from animal fats as well. Double check with your supplier if they don’t state the origin—that said, I have never found magnesium stearate made with animal-derived stearic acid.
Recommended starter amount 30g (1oz)
Where to Buy it  Buy it from an online DIY ingredient supplier or Amazon.

Some Formulations that Use Magnesium Stearate


Posted on

January 22, 2019