Article by: Kelly Dobos
Pearlescent pigments can add satiny shimmer or a sparkling glitter effect to cosmetics. Pearls can also add color and change sensory properties. Here are some things to keep in mind when selecting pearls for cosmetic formulations.
Picking Pearlescent Pigments
Properties affecting the appearance of a pearlescent effect pigment include size, shape, substrate type and coating.
Particle size: A small particle size around 15 microns will result in a satin-like appearance while a larger particle size in the 100 micron range will give sparkle.
Particle Shape: Irregularly shaped platelets will have low gloss and transparency while a smooth surface will have high gloss and transparency. Borosilicate flakes demonstrate high sparkle and transparency due to a very smooth surface.
Substrate type: Natural mica is a cheap, classic substrate but lacks the high color purity of synthetic mica (INCI: Synthetic Fluorphlogopite). Compared to natural mica, synthetic mica has significantly lower residual heavy metals.
Coating Type: Titanium Dioxide coating will give an iridescence that varies in color as the thickness of the coating increases. Colored coating materials (organic pigments and iron oxides) will give absorption-based color.
Formulating tips for pearlescent effect pigments
Pearls are fragile and should not be milled or exposed to harsh mixing. They are truly stir-in ingredients and should be added to formulas late in the process.
All pearls need to be suspended in formulation. This means you’ll need something in your formula to increase the yield point of the system. In liquid formulas, an ingredient like Carbomer or Xanthan gum can do this.
Naturals micas can darken with oil absorption, including sebum from the skin.
Bismuth Oxychloride can darken with light exposure and should be protected with opaque packaging.