Glass microspheres offer a number of other advantages for cosmetic or personal care applications. Solid glass microspheres offer cosmetic formulators tools to create new “looks” and to solve old problems that talc or other ingredients cannot. Light interacts with objects and is “observed” by the eye primarily as specular or diffuse reflection. The type of reflection depends on the “surface” from which the light is being reflected—basically, the underlying particulate matter of the reflecting substance. Most materials are composed of particles of irregular or uneven crystalline structures. These uneven “surfaces” reflect light as diffuse reflection where the reflected light bounces off randomly and in all directions. Glass has a smooth “surface” so it lacks the mechanism of many uneven surfaces to diffuse light in random directions and can only reflect light specularly: the reflected light bounces back in a consistent direction and angle. Virtually all materials exhibit both types of light reflection at the same time. Glass microspheres, however, offer a uniquely efficient combination of specular and diffuse reflections that provides new approaches to disguising skin imperfections. Some of the light hitting a glass microsphere bounces back directly off the smooth glass surface. Because of the transparency of the glass sphere, however, much of the light is transmitted through the sphere and is reflected off the underlying uneven skin surface. The combination of the two types of reflection “fools” the eye and the resulting “fuzzy” focus distorts and disguises any underlying wrinkles, discoloration or uneven pigmentation. No other sphere offers this combination: ceramic spheres are not transparent and cannot reflect light the same way and hollow glass spheres are not as transparent so less light is transmitted. P2011SL are the smallest, commercially available solid glass microspheres, with an average diameter in the range of 3 to 6 microns. In cosmetic applications, they act as functional enhancement pigments or additives, and as optical spacers and color intensifiers. BecauseP2011SL microspheres are clear and solid glass, they function as magnifying lenses and make any pigments or mica particles they surround appear richer, deeper, and more intense in color. Microspheres can significantly reduce glazing effects when they are added to face and eye shadow powders. As a functional enhancement additive, P2011SL spheres offer a simple and elegant method for formulators to embody “soft focus” or “optical blurring” ingredients into makeup and skin care products. This phenomenon occurs because of the way light is reflected from glass. Light falling on glass particles is reflected back at an angle from many microscopic points rather than directly. The effect of this “scattered” reflection is to confuse the eye into seeing the skin as brighter; the reflection “disguises” the appearance of blemishes such as fine wrinkles and makes the skin look younger. Geometrically, P2011SL spheres function as flow enabling or anti-mottling agents.
The visual functionality of P2011SL spheres depends on their interaction with ambient light, so formulations should be designed to allow light transmission and to position the P2011SL microspheres at or near the surface of the formulation. In water or solvent-based formulations, P2011SL spheres are typically added at levels ranging from 5% to 10% (calculated as the ratio of the dry weight of the microspheres to the dry weight of the other ingredients) depending on the intensity of color and the effect desired. When loading levels exceed 10%, P2011SL spheres shift to become a flatting agent, resulting in a matte or low gloss effect.