Silk Powder

Overview

Silk powder is produced from natural silkworm cocoons. The raw silk fibres are degummed in a mild alkaline solution to remove sericin (the sticky outer protein layer), leaving pure fibroin protein. The fibroin is then broken down, washed, dried, and micronised into an ultra-fine free-flowing powder. Particle size is typically in the 1-10 micron range, with the finest grades approaching 1 micron.

The finished material is a pure white, almost weightless powder with a faint silky odour. It contains 18 amino acids that make up the fibroin protein. Cosmetic-grade silk powder is sterile-friendly and free of the sericin allergen.

Shelf life is 2-3 years stored cool, dry, and sealed against humidity. The powder is hygroscopic and will clump if exposed to high humidity.

What it does in a formula

The main role in mineral makeup and pressed powders is sensorial and optical. The micronised silk particles fill in micro-irregularities on the skin surface, scattering light slightly to produce a soft-focus effect that blurs fine lines and pores without looking matte or flat. The result is a finish that reads as “velvety” or “silky” rather than powdery.

It also improves the slip and spreadability of mineral foundations and powders, reducing the dragging or grippy feel that high titanium dioxide and zinc oxide loads can cause. The fibroin protein itself is mildly hygroscopic and contributes a small amount of moisture retention at the powder layer.

In leave-on lotions and creams, very small percentages add a silky after-feel that gives the product a more luxurious finish.

How to use

Disperse into the oil phase for emulsions, or blend uniformly into the dry powder phase for mineral makeup. For pressed powders, sieve thoroughly to avoid clumping. Not soluble in water — disperses but does not dissolve.

Usage rates by product type:

• Mineral foundation powders: 2-5%
• Pressed face powders: 1-5%
• Loose setting powders: 1-3%
• Body powders: 1-3%
• Liquid foundations: 0.5-2%
• Face creams (silky finish): 0.5-2%
• Eye shadows (slip): 1-3%
• Blush and bronzer: 1-3%

Best for / Worst for

Best for: mineral foundations and pressed powders, soft-focus finish positioning, makeup where slip and skin-feel are part of the claim, leave-on creams wanting a silky after-feel, premium colour cosmetics.

Worst for: vegan-positioned formulas (silk is an animal-derived ingredient), water-based products without an oil phase (it disperses but does not solubilise), budget product lines (cosmetic-grade micronised silk is relatively expensive), strict cruelty-free standards that exclude all silkworm-derived ingredients.

Common pitfalls

Vegan positioning. Silk is produced from silkworm cocoons, which conventionally requires killing the silkworm. It is not vegan, and most certified cruelty-free standards exclude it. Brands with vegan or strict cruelty-free claims should not use silk powder.

Inadequate dispersion. The ultra-fine particles can clump if added to a product without proper sieving or mixing. For pressed powders, sieve at least once through a fine mesh before pressing. For emulsions, disperse into the oil phase with mixing before combining with water.

Confusing it with hydrolysed silk. Silk powder is solid micronised fibroin, dispersed in the oil or powder phase. Hydrolysed silk is a water-soluble protein for serums and leave-ons. They are not interchangeable.

Humidity-related clumping. Silk powder is hygroscopic. Once a container has been opened, store it tightly sealed with a desiccant if possible. Pressed-powder products made with silk should be packaged with airtight closures.

Substitutes

• Sericite mica — mineral alternative for soft-focus optical effects.
• Boron nitride — mineral alternative for silky slip.
• Hydrolysed silk — water-soluble silk protein for water-based formulas.
• Nylon-12 — synthetic alternative for slip and soft-focus (not natural).