Hair removers, or depilatories, are products designed to chemically or physically remove undesirable hair from areas on the body. Hair removers are made by mixing together the appropriate raw materials in large stainless steel tanks and then filling them into individual packages. In use for thousands of years, they continue to be an important part of many people's everyday hygiene. Currently, new hair removers are being investigated which are less irritating, more effective, and longer lasting.
Epilatories were the first type of hair removers. The most common of these products is an epilating wax. This product is heated and spread on the skin in the desired area. It is then allowed to cool and harden. The mass of wax is then rapidly removed, pulling with it about 80% of the hairs. It is a slightly painful procedure and a mild anti-+ septic is typically applied to protect against skin irritation. Epilatories have not been widely used by individual consumers, how-ever they are popular in beauty salons.
While epilatories continue to be an important method of hair removal, depilatories are much more common in personal care. Depilatories rely on a chemical reaction between materials in the formula with components of the hair. When the depilatory is applied to the skin, a component in the product, such as thioglycolic acid, reacts with the protein in the hair and weakens it. The hair can then be removed from the skin by gentle wiping, scraping, or rinsing. This is effective on any part of the hair structure that is above the level of the skin.
The compounds in the depilatories, which react with hair, also react with protein in the skin, albeit at a much slower rate. For this reason, depilatories must be left on the skin for only a short while. The manufacturers of depilatories realize this and strive to develop formulas, which have only minimal negative effects on skin. Typically, if a consumer follows the directions as stated on the package, no problems will arise. Epilatories generally will not have a negative effect other than physical irritation on skin since they do not rely on a chemical reaction to function properly.
The first step in producing a hair remover, or any personal care product for that matter, is developing a formula. Cosmetic chemists use their knowledge of standard cosmetic ingredients, consumer research information and various other types of information to construct their formulas. Since hair removers can be sold in many different forms including creams, gels, lotions, and aerosols, the formula must be adapted to the product form. The formulas are first prepared in small beakers in the lab so aspects of the formula can be evaluated. Tests for product effectiveness, stability, and safety are all completed at this point. Other studies such as consumer acceptance testing may also be completed.
Hair removal from various parts of the body has been an important part of beauty for thousands of years. The earliest recorded use of hair removers is found in ancient India where hair removal was highly desirable. This society frequently used abrasive pastes and resinous plasters to physically remove hair. In the Middle East, a lime mixture was used for a similar purpose. Other materials, such as antimony and arsenic compounds, were also used; however, it is now known that these materials are quite toxic, and their use has been discontinued.
The earliest hair removers used a method of hair removal known as epilation, or physically pulling hair out. Common procedures included using devices like tweezers to pull hair out selectively or waxes which pulled hair out in large masses. Since hair removal by physical means was often a painful experience, scientists worked on developing formulas, which would chemically remove hair. Little progress was made in this area until about 100 years ago when it was first reported that barium sulfide was used for this purpose. A few years later a similar idea was patented in the United States. Cream depilatories were first introduced in the 1920s and many more patents were issued during the 1930s. Thioglycolate depilatories, which were first introduced in 1938, have become the most important hair removers.
There are many different materials that have been used in hair remover formulas. Some of these materials are responsible for the hair removing properties of the product while others are needed to improve the product's aesthetics.
As suggested, depilatories and epilatories remove hair in a very different manner. Obviously, they then require different compounds to function. A standard epilatory may be composed of a wax such as beeswax and a sticky, polymeric resin. The wax provides the setting action needed for peeling the product off the skin and the resin helps bind the material to the hair. The active ingredients used for depilatories include thioglycolate salts and sulfides. Thioglycolate salts include materials such as calcium thioglycolate and potassium thioglycolate. In an aqueous solution at the proper pH, they are converted to an acid, which then affects the hair. Sulfides such as barium sulfide or strontium sulfide are also used because they react more rapidly than thioglycolates how-ever, they have other characteristics which make them less appealing. Since pH is critical to the proper performance of depilatories, ingredients such as sodium hydroxide or calcium hydroxide, which adjust the pH, are included.
In addition to the hair removing ingredients, other compounds are necessary to complete formulation. This includes diluents, emollients, thickeners, fragrances, and colorants. Water is used most often as a diluent for depilatories because it is compatible with a large range of raw materials, non-irritating, and inexpensive. Since epilatories are waxes, they are not compatible with water so mineral oil is typically used as the diluent. Emollients are included in formulations to reduce the harshness of the formula and improve the feel. Materials like oils, silicones, and esters are all examples of commonly used emollients. Depending on the product's form, a thickening agent may be required. These materials are typically polymers, surfactants, or modified clays. For aerosol products, a propellant is needed.
To improve the aesthetics of the formula, fragrances are included. These fragrances must be specially designed to overcome the generally offensive odor of the hair removal ingredients. For cream or lotion products, emulsifiers are needed and dyes are used to modify the color. Various other ingredients such as preservatives, antioxidants, extracts may also be included.
Beyond the ingredients that go into the hair remover formula, packaging components are another important raw material. Bottles are primarily used and are made of plastics such as polyvinyl chloride (PVC) or high-density polyethylene (HDPE). For aerosol products, a steel or aluminum can is used. The outer graphics can be either directly silk screened on to the package or an adhesive label can be applied.
The process for making a hair remover can be divided into two steps. First, a large batch of the product is made, and then it is filled into the individual containers. While there are many different product forms the hair remover may take such as creams, aerosols, or waxes, the following description
When the controls are set, the raw materials can be added. In most formulas, water is added first by being pumped in at the appropriate volume. The mixer is then turned on and the other raw materials are added in the order called for in the formula. These raw materials are either poured into the batch from bags or 55 gal (208.2 1) drums. As each goes into the tank, it is thoroughly mixed. Depending on the formula, the batch is heated and cooled as necessary to help the raw materials combine more quickly. A typical 3,000 gal (11,355 1) batch of depilatory may take anywhere from two to five hours to make.
To produce a consistent product, quality control inspections are done throughout the manufacturing process. At the start, the raw materials are checked to ensure that they meet the manufacturer's specifications. Typically, quality control chemists sample incoming raw materials and run numerous tests before qualifying them. These tests may include checks for appearance, pH, odor, or viscosity. More complex testing may also be performed. During manufacture, the batch of hair remover is periodically tested to make sure that a functional product will be produced.
While the product is being filled, quality inspectors are stationed along the entire filling line. These workers watch the containers as they pass by and pull off any which are defective. This includes those that are inadequately filled, have misplaced labels, or otherwise damaged. Regulations also require that samples be periodically checked for microbial contamination during filling.
The market for hair removers is relatively small compared to other personal care products such as shampoos or conditioners, so only minimal research is currently being pursued. The focus of this research has been on making products that are less irritating and more moisturizing to the skin, lower in odor and more effective. Irritation is likely to always be a problem for all depilatories that chemically alter proteins so compounds, which weaken hair in other ways, may be developed. Beyond depilatories and epilatories, new drugs could be developed which can inhibit the growth of hair from follicles. This might represent a kind of permanent hair remover.
Knowlton, John and Steven Pearce. The Handbook of Cosmetic Science and Technology. Oxford: Elsevier Science Publishers, 1993.
Umbach, Wilfried. Cosmetics and Toiletries Development, Production, and Use. New York: Ellis Horwood, 1991.
Breuer, Hans. "Depilatories." Cosmetics & Toiletries 105 (April 1990): 61-66.
— Perry Romanowski