Cosmetics: “articles intended to be rubbed, poured, sprinkled, or sprayed on, introduced into, or otherwise applied to the human body…for cleansing, beautifying, promoting attractiveness, or altering the appearance” FD&C Act, sec. 201
Stability Tests. Different tests that provide evidence on how the quality of a cosmetic product varies under the influence of a variety of environmental factors such as temperature, humidity, and light. They also aim to establish a shelf-life for the cosmetic product and recommended storage conditions.
Shelf -Life. The time interval that a cosmetic product is expected to remain within specification provided if stored under the conditions defined on the label in the proposed containers and closures.
Beaker: the Container. Made with Pyrex glass, can resist high temperatures and it’s perfect for heating, stirring and pouring. Cheap and versatile, can’t work without it. It exists in several different sizes (example 50, 250, 500 ml).
Centrifuge: a device that separates fluids according to their density. The separation is achieved through vessel’s high rate spinning. Fo example, in the case of an o/w emulsion, the oil tends to go on top due to its higher density.
Hot plate: it’s what you should use to heat beakers. Ceramic coated surfaces are the best, but aluminum. A hot plate can include a magnetic stirrer, allowing the liquid to be stirred. When making your decision, key factors to consider are: the size, the presence of the stirrer, the surface’s material, temperature range, digital temperature indicator (very useful for those processes where the temperature has to be set and controlled).
Spatula: another excellent lab tool. Always pick stainless steel, one size is enough for most tasks . For bigger tasks , use metal spoons.
Water. Water is the most common solvent used in cosmetics.
Emulsion. An intimate mixture of two essentially immiscible liquids that exhibits an acceptable shelf life.The most common types of emulsions in cosmetics include water as one of the phases and oil as the other. If the oil droplets are dispersed in water, the emulsion is termed oil in water o/w) and vice versa. Very popular are also water in silicon emulsions.