Loose powders can come in any type, size, color, flavor, etc. They include, dusting powders, finishing powders, foundations, perfumed body powders, cheek powders, eye shadows, etc. The basic formula for each of these is similar, using many of the same ingredients to deliver the properties exhibited by each. For example, foundations, mineral powders, finishing powders, cheek powders and eye powders all contain the same conventional color additives that are found in every other color and decorative cosmetic product. Loose powders usually do not contain as high a color level as their pressed counterparts, but particle size reduction is usually performed using the same type of grinding apparatus. Particle size is critical to a powder product’s feel and performance.
Dusting powders and perfumed body powders are a bit different in that they must contain ingredients that have a high oil or water absorbance. Body powders are usually applied after a bath or shower, and water absorbance is the key property in them. In a perfumed body powder, high levels of fragrance oil are used. High oil absorbance is required to keep the powder flowing freely without caking due to the high level of oils used in the product. Body powders and fragrance powders are usually marketed in loose form in a box or in a shaker canister. Since both are for after bath or shower and most likely stored in a hot humid environment, they need to be formulated to not absorb any moisture from the air. The right ingredients will prevent this; usually a balance of ingredients that will absorb body moisture but not environmental moisture. The proper balance of absorbent silica and nonabsorbent silica will work best here.
In all cases, loose powders must have adequate adhesion properties so that they will have acceptable wear on the skin but will also be lightweight. Aside from the perfumed body powders, most other loose powders contain the same small level of liquid binder. This liquid binder is in the formula at just enough concentration to prevent the product from dusting and getting everywhere, as well as aid in the product’s adhesion to the skin. In most cases, loose powders can be applied with a puff, although most people prefer to use a makeup brush.
Pressed powders contain many of the same ingredients as the loose powders, but pressed powders are contain a significantly higher amount of liquid binders to hold the formula together. The higher level of liquid binders are needed for compacting and pressing the formulation into aluminum or tin-plated pans,and to improve on the adhesion properties on the skin. The binders also contribute greatly to the overall feel of the product on application. Many different liquid (and solid) binders can be used depending on the properties desired in the particular type of powder. Pressed powders usually require an applicator, but makeup brushes can be used in some cases.
The use of a jet mill is preferred in pressed powder foundation to give the product its elegant feel characteristics. This will be evident by running a finger over the surface of the powder. The jet mill’s mechanism is a bombardment of particles against one another, resulting in a much smaller particle size (~1 micron) and a unique spherical shape. These properties contribute to feel as well as compaction and stability of the product. Powders that are jet milled have much better drop test results than conventional powders that are ground with a hammer mill or micro-pulverizer. These powders can have an irregular shape and are much larger (3-5 microns) than jet milled powders. These powders are also more difficult to press consistently because of this and drop test results can vary. Powder presses must be constantly adjusted to account for the differences in formula and high binder levels.
In all cases, powders may contain the same ingredients that contribute to feel and application. Many talc-free products have been introduced on today's market. Talcs are being replaced with natural materials or synthetic polymers. Some of these ingredients include polymethylmethacrylate (PMMA), polytetrafluoroethylene (PTFE), boron nitride (BN), various types and grades of silica (SiO2), various nylon powders, micas, sericites, etc. These ingredients are on many powder cosmetic ingredient labels at fairly high levels because of their unique feel, application and visual properties. Some provide a ball-bearing effect to provide a smooth glide when applying to the skin.
Pearls, mainly mica-based ingredients with titanium dioxide and colors, are widely used in powders for they coloring properties and visual effects. They exist in many colors and many particle sizes, but are at a maximum of 150 microns in eye products. They are all available from a number of sources. Other pearlized ingredients such as borosilicates are used in powders and are based on ceramic glass for their reflective, scattering and other unique visual effects.
Color, feel, application and special visual effects (and sometimes fragrance) along with long wear are the main properties behind all types of powders.