Calcium stearate

Calcium stearate explained

Calcium stearate is a fine powder. The supplier specification lists it as soluble in alcohol and dispersible in oil. Chemically, it is the calcium salt of stearic acid, part of the metal stearate family, together with magnesium and zinc stearate. The supplier CoA confirms the grade and INCI.

Why it is used in makeup

Calcium stearate helps powders stick together when pressed and adhere to skin when applied. It also repels water, so powders resist moisture and caking. In loose powders it improves flow and slip.

Product formats

Pressed powders

Pressed setting powders, blushes and eyeshadows use metallic stearates as binders. They help the powder form a firm cake that still picks up well on a brush.

Loose powders

In loose powders, a small amount improves flow and adhesion.

Sticks and balms

Oil-based sticks can use it to adjust texture and reduce sweating.

Creams

In creams, it can help thicken the oil phase and stabilize texture.

Processing

For powders, blend calcium stearate with the other powders in a mixer, then add the binder oils and mill or sieve. For oil-based products, disperse it in the warm oil phase with good mixing.

Partners

Talc alternatives such as mica and starch, Boron Glow (Boron nitride) and Calamine powder suit face powders. Binder oils such as esters complete pressed formulas. Makeup texture helpers are listed in the actives catalog.

Testing

Check pressed cakes with a drop test and payoff test. Check loose powders for flow and caking in humid conditions.

Claims

Calcium stearate is a texture ingredient, so claims are about the finished product: silky, long-wearing powder, smooth application.

Characteristics

Form: fine powder. Solubility: alcohol; disperses in oil. Type: metallic stearate. Uses: pressed and loose powders, sticks, balms, creams. Grade and INCI: supplier CoA.

Original recipe: pressed setting powder, 100 g

Mica 50.00 g, corn starch 20.00 g, silica 10.00 g, calcium stearate 6.00 g, boron nitride 5.00 g, iron oxides 2.00 g, caprylic/capric triglyceride 5.00 g, ethylhexylglycerin 0.50 g, caprylyl glycol 1.50 g. Blend the powders, add the liquids slowly while mixing, sieve, then press into pans.

Choosing a stearate

Calcium, magnesium and zinc stearate behave similarly but differ in feel and adhesion. Zinc stearate is often chosen for strong adhesion and a creamy feel, magnesium stearate for a soft feel, and calcium stearate for good water repellence and flow. Many brands test two or three and choose based on payoff and wear. Keep notes on each test, including how firmly the cake presses and how well it picks up on a brush.

Pressing tips

Pressed powders need the right binder level and pressure. Too little binder makes cakes that crumble; too much makes them hard and glazed. Start with a small batch and adjust in steps, testing each pan with a drop test from a set height onto a hard surface. Record the pressure used with each formula.

Humid climates

In humid weather, water-repellent stearates help powders resist caking and keep a smooth finish all day. Test powders in a humid cabinet if you sell in warm regions.

Talc-free trends

Many shoppers look for talc-free powders. Mica, starch and silica with a metal stearate binder make a good talc-free base.

Safety and handling

Fine powders can become airborne during mixing. Use dust extraction or a mask in production, and keep containers closed.

Lot records

Keep the CoA with each batch and compare the whiteness and feel of each new lot with a retained sample.

Record the lot number in your batch log so every production run can be traced back to its certificate of analysis. Retain a small sample of each lot for at least the shelf life of the finished product, since it makes later quality questions much easier to answer.

Storage

Store closed in a dry place. Close the container after use.