Tony O'Lenick explains that the basic categories of cosmetic formulas include: solutions, creams/emulsions, lotions, ointments/pastes, suspensions, tablets, powders, gels, sticks and aerosols. Here, he turns to Perry Romanowski, of Brains Publishing, to discuss the differences between these ten types.
These are the simplest type of cosmetic formulas and are used for a wide range of products such as shampoos, body washes, hand cleansers, colognes, etc. They are homogeneous mixtures of soluble ingredients. To make them, the main container is filled with the main diluent (usually water), and the rest of the ingredients are mixed into the diluent. Sometimes warming the system slightly will increase the speed at which a formulator can make them.
The majority of cosmetics use raw materials that are not compatible, and when this incompatibility occurs, a cream or emulsion is used. Emulsions are pseudo-stable mixtures of immiscible liquids dispersed in another liquid. They are used for products such as hand moisturizers, makeup, hair conditioners, sunscreens, etc. To create them, a formulator needs three formula components including an oil phase, an aqueous phase and an emulsifier. The formulas are made by heating the oil and water phases separately, then mixing them together (along with the emulsifier). Once they are hot, they are cooled with thorough mixing. The result is a cream with tiny particles dispersed in the diluent phase.
Creams are not always appropriate for some applications because they can be heavy or greasy. In these cases, the lotion form is used. Lotions essentially are thin creams. They are used for facial moisturizers, leave-in hair conditioners and moisturizing cleansers. As lotions are emulsions, they are formulated the same way as a cream. They are generally easier to formulate because the formulator does not need to wait for the emulsion to thicken upon cooling.
These are very thick products that are used for hair styling and medicated skin products. Usually they are anhydrous (meaning they do not contain water), sticky and greasy. Common ingredients used to create pastes include petrolatum, lanolin or dimethicone. Making them is a simple matter of heating up the raw materials and rapidly mixing them until they are dispersed.
Suspensions are another product form for delivering incompatible ingredients. Unlike creams, typically they are clear products with visible particles, like gelatin beads or inorganic minerals (e.g., titanium dioxide) suspended throughout the formula. They are used for sunscreens, hand washes or shampoos. Their creation involves a polymer or clay to give the formula some internal suspending structure. Here, ingredients like carbomer or bentonite clay are useful.
Color cosmetics are often formulated into a tablet. Tablets are physically blended solids that are held together by pressing them into shape. Special equipment is necessary to create these products. They are also generally more expensive.
One of the most common types of product forms for color cosmetics is powders. Powders are also used for baby powder and foot powder. They are mixtures of solid raw materials blended together into a fine powder. Typical ingredients include talc, silicates and starch. Special equipment is needed when making these products, as the fine powder can be dangerous.
Another common form of cosmetic products is gels. These typically are thick, clear products that have a property known as shear thinning. This means they stay thick until a force is applied that makes them thin and flowable. Gels are used for hair products, body washes, shaving products and in toothpaste. They are made by using a gelling agent such as an acrylic polymer, a natural gum or a cellulosic thickener.
Sometimes a formulator must create products the consumer does not touch, such as lipstick or underarm deodorant. In these cases, a stick form is used. Sticks are solid delivery forms that deliver active ingredients through a rubbing action. They are created by using materials that typically are solid at RT. The ingredients are heated until they melt, mixed and poured into either a mold or the final container. When they cool, they take the shape of their packaging.
Aerosols are more of a packaging product form than a specific formulation type. An aerosol can actually be created from almost any cosmetic formulation with the right can, propellant and nozzle set-up. Aerosols are any cosmetic delivered from a pressurized can. They are composed of a concentrate and a propellant. The formula in the can is created similar to any other cosmetic and the can is filled with this formula. The can is sealed and pressurized using the appropriate propellant. Recent volatile organic compound regulations have reduced the use of aerosols in cosmetic products.