The invention relates to rods or rollers of the type used by hair stylists and beauticians to give a permanent curl or wave to naturally straight hair.
The commonly practiced method of imparting a lasting curl or wave to hair comprises three basic steps. First, strands of hair are wrapped around rods or rollers and clamped in the wrapped configuration. Then, a chemical agent is applied to the wrapped hair, which causes the hair to undergo a chemical change, enabling the inner structure of each strands of hair to conform itself more or less to the curvature of the rod around which it is wrapped. Finally, a fixative step is carried out to stop the action of the chemical agent. The fixative step typically involves the application of a second chemical agent, or heat, or both. These steps are frequently supplemented with a shampoo or other pre-moistening step and conditioning steps for damaged, unhealthy or over-porous hair.
Several difficulties are routinely encountered in carrying out the above process. There is a natural tendency to wrap the hair too tightly on the rods. Tight wrapping prevents the chemical waving lotion from uniformly and thoroughly penetrating the strands of hair, and it interferes with the natural expansion of the hair under the action of the waving lotion. The result is irregular, imperfect and short-lasting curls. Moreover, tight wrapping can lead to hair breakage and causes neighboring strands of hair to rub against one another in a "sandpaper" effect, giving the hair a frizzy appearance.
Other difficulties routinely encountered in the application of the chemical waving agent relate to the possibility of injury to the patron. Some commonly used waving solutions are highly alkaline, having a pH on the order of 9. Any prolonged contact of such waving solution with the patron's scalp, even in small amounts, is to be avoided. In fact, in order to be certified by appropriate regulating bodies, cosmetologists are frequently called upon to demonstrate a proficiency at applying the proper amount of waving solution to wrapped rollers without allowing any to contact the patron's scalp. Other compounds are available which have a lower pH, but even these can cause irritation in a healthy scalp and will certainly cause irritation where lesions of the scalp are present. Cosmetologists who work with the waving solution repeatedly throughout the day typically wear rubber gloves or protective cream to guard against such irritation.
Long hair exacerbates the above difficulties to such an extent that a patron with naturally straight long hair simply cannot obtain a permanent giving a satisfactory gentle body wave to the hair. Long-haired patrons in the past have resigned themselves to permanents with tight curls and a frizzy appearance, while often having to suffer the irritations of the chemical waving lotion of the scalp.
The problem of giving a gentle body wave to long hair lies in the rollers. A body wave, in distinction to a curl, requires a large diameter roller. Known rollers are subject to any of the following deficiencies when used with long hair; they do not facilitate full or uniform saturation of the hair; they require an excessive amount of lotion to achieve saturation with the result that the lotion invariably comes in contact with the scalp or skin of the neck or face; long hair tends to wrap too tightly around them with resultant frizziness; they have undesirable mechanical limitations; for example, some rollers are not reusable, and others employ intricate and expensive constructions to provide means for applying the chemical agent under pressure and the like. All of the known rollers represent a tradeoff between these deficiencies, and the tradeoff becomes greater as the diameter of the rod is increased.