The most striking element of any lipstick is, without a doubt, the color—and red lipgloss is especially iconic today. Cleopatra is perhaps one of the most notable figures from historical times who reputedly added color to her lips using crushed cochineal beetles to extract the red carmine color.5 It also is reported that before Cleopatra, more than 5,000 years ago, Egyptians stained their lips using ochre and iodine.6 From this and other early forays into makeup application, the world’s obsession for applying lip color began.
Since these first, crude methods of production, lipstick has thankfully become much more sophisticated. In today’s world, consumers expect lipstick to go beyond color application, and women’s minimum expectations for performance appear to increase with each passing decade—mirrored with the need for cosmetic companies to constantly deliver on brand promises and product performance claims, and to provide stand-out-from-the-crowd effects. The lipsticks of today are still recognizable descendents of the mass-produced formulations that began in the mid-twentieth century and consist, for the most part, of waxes, oils, alcohol and pigments. During lipstick’s development, the industry has witnessed a number of evolutionary cycles, but the core formula type has remained fairly constant, and each of the ingredients plays an important part in the structural and aesthetic qualities of a lipstick.
For example, commonly used waxes such as beeswax, carnauba and candellila give substance and form to the final product. Therefore, balancing the correct wax blend is an important consideration for the formulator. The melting point of waxes impacts the softness of the end product; low-melting point waxes may render a softer stick that is difficult to contain within its pack and makes application messy and uncontrollable. A texture that is too hard can result in a difficult and unpleasant application with a poor sensorial experience.
Before inserting a lipstick into its container, it must be molded into the familiar bullet shape. Traditional molding equipment is made from aluminium or steel, and the process of filling involves simply pouring the hot, molten formula into the metal split mold. Once the formulation has cooled and set, the molds are split and the lipstick bullets are removed. Until the 1970s, this process employed manual labor, which was considerably intensive since it involved cleaning the molds and maintaining product overspill. The process for molding lipsticks was automated in 1971 when Weckerle invented the first fully automatic molding machine.7 Automation gave the industry a distinct advantage of quicker, more efficient production, in turn giving manufacturers the ability to deliver a higher volume of product. Essentially, the automated process still incorporates pouring the hot, liquid formulation into steel or aluminium capsules but moves through the various stages of molding on a conveyor.
Arguably, some of the most practical raw materials, in terms of lipstick manufacturing and within formulations themselves, come in the form of silicones. In the industrialization of lipstick molding, silicones have enabled the creation of soft molds—a more modern counterpart to the earlier metal molds. These are commonly used and provide greater scope for the branding, such as for imprinting logos or specializing the design of bullets themselves.
Further experimentation with different silicone types in the soft filling process could hold as-yet unrealized potential for lipstick production, especially taking into account the variety of characteristics that silicone compositions can offer in terms of hardness and porosity. For example, changing the hardness of the silicone can impart different effects on the surface of the mold, which can be especially useful with soft or sticky lipstick formulations. The silicone maintains a smooth and shiny surface that could not be obtained if a metal mold were to be used. For the traditional hard-filling process, ceramic, Teflon (a trademark of DuPont) and resins such as acrylic can also play an important role in mass manufacturing (see Table 1).