Some ingredients can be unstable, irritating to skin or difficult to incorporate into cosmetic compositions. It is often necessary to trap these sensitive substances first into a delivery vehicle in order to formulate an effective, stable product that provides perceivable benefits.
For many centuries, powders of natural origin (powders such as silicates, carbonates and oxides) have been used in cosmetic formulations as fillers, texturing agents or coloring materials. For example, micas, which are silicate derivatives, have been applied in makeup and skin care products for their optical effects as well as their texturing properties.
Today, a better understanding of the physical structure of modified micas gives the formulator several opportunities for using them as a unique delivery system and as a protection for a variety of hydrophilic compounds. Thus, for the first time, the field of the formulation will open to the mineral substances as encapsulating materials.
In this article we will describe one of these mineral substances: magnesium sodium fluorosilicatea, a modified mica. We also report on experiments that test this material’s behavior under conditions of hydration and dehydration, and a second study on the material’s ability to encapsulate glycerin. Finally, we offer some formulations, tests and results of using the modified mica in cosmetic applications.
Magnesium Sodium Fluorosilicate
Magnesium sodium fluorosilicate belongs to the new generation of modified micas with promising encapsulation capabilities. This special grade of mica, which we will call MSG, is synthesized by calcination at 800°C for several hours using talc and a sodium silicofluoride under controlled atmosphere. The result is a sodium fluorine mica characterized by a particular crystalline structure with unique properties. This mica has a lamellar structure. In association with a median particle size less than 10 μm, it provides a superior tactile feel to cosmetic formulations.