The aesthetic appeal of a pearlized product is undeniable. Pearlescence imparts an elegance and richness to a product that can elevate its appearance from an ordinary to a premium look. Depending on the type of product, this look can be achieved by different methods.
For personal care and beauty compositions, an approach commonly used is the addition of opacifiers such as Ethylene glycol mono- and distearates within a concentration range typically between 1% and 2%. Hallstar® EGMS and Lexemul® EGDS are two such examples that are listed on Prospector.
For optimal effect, these ingredients are added at a temperature above 70˚C, which should be maintained while mixing, to allow the material to fully melt and be finely dispersed. Crystals are then formed in-situ during the cooling process and are suspended in the base, resulting in the pearled effect. Many factors can affect the size of the crystals formed and ultimately the appearance of the pearl in the final product:
- Particular stearate used
- Cooling rate
- Rate of stirring
- Composition of the base
- Viscosity of the base
Fatty acid soaps created in-situ by partial neutralization with an alkali base have also been used to deliver the desired sheen and luster of a pearlescent product – an approach that has been documented in published patent documents1,2.
According to the authors, a key factor in achieving the luster effect is careful control of the level of soap formed in the composition, with soaps of stearic acid being particularly effective at delivering a pearly product.
Concentrated pearl mixtures have been en vogue for some time and are widely used. They offer the formulator convenience, the ability to utilize a cold process and the ability to deliver a more consistent product, since these mixtures are not sensitive to the same variables described above. These blends are typically comprised of one of the aforementioned stearates combined with a surfactant or surfactant blends. These concentrates have evolved since first being introduced, with present-day compositions formulated to be milder and more regulatory-compliant than earlier versions. Examples listed on Prospector include: Quickpearl™ PK3 Pearlizing Agent; Euperlan® Green; and Perlogen® SF 3000.
Inorganic natural substances such as Mica or coated Mica are also commonly employed as pearlizing agents, especially in color cosmetics where they contribute sparkle and sheen – attributes that are particularly desirable in that product category.
- Huang, L; Harichian, B; Shanling, S. Pearlescent Liquid Cosmetic Composition. US Patent Application 20100105742, April 29, 2010.
- Huang, L; Harichian, B; Shanling, S. Pearlescent Liquid Cosmetic Composition, WO Patent Application 2010046406, April 29, 2010.
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