Today’s safe, easy-to-use permanent wave systems were anything but easy to create. In 1910, K.L. Nessler, a hairdresser living in London, obtained a patent to produce permanent waves by heating hair wound on a mandrel with an aqueous alkali solution. The temperature of the hair was 200-250°F and was reached electrically. Later, chemical heating pads (such as the exothermic reaction of mixing calcium oxide and water) was used. N.G. Hillier describes the hazards of using heating pads as originally designed.1 “It took all day to give a permanent wave…Women bragged about their burns to other women. It was torture. The heaters were so heavy that only a few curls could be baked at a time. The pads would stick to the heaters. It was necessary to tap the heaters with a hammer to release them…Sometimes the hair would come off with the pad.”
Constant improvements on this process finally produced a cold waving system in the late 1940s which I consider a “breakthrough” invention. The cold wave is superior because of its speed, simplicity, efficiency and level of safety, although the timing of the treatment should be closely monitored. The cold wave is possible due to the use of ammonium thioglycolate (thio) as the reducing agent to break the cystine bonds of the hair as it is wound in the desired configuration. Ammonium hydroxide (ammonia) is the usual alkali used to swell the hair and enable the thio to penetrate rapidly. Because ammonia is a volatile liquid, it evaporates quickly during the process, allowing the pH to drop and causing less damage than a fixed (non-volatile) alkali such as sodium hydroxide. The usual pH of this conventional perm is 9.5 and the usual time on hair is 10 minutes. Resistant hair might be processed for 15 minutes, but tinted hair is usually ready in five minutes.
A typical formula might be:
Perm for Normal Hair
Water (deionized)q.s. to 100
An ethoxylated oil may be added for some conditioning properties.
Before applying the above formula, the hair is wound on waving rods, the diameter of which determines whether the resultant curls will be tight or loose: the narrower the rod, the tighter the curl.When the processing time is over, the hair is rinsed and neutralized (actually oxidized) for five minutes while it is still on the rod. The neutralizer is usually 2% hydrogen peroxide at a pH of 3 to 4. The neutralizer formula can be opacified, perfumed, thickened or emulsified.
A formula for a simple opaque neutralizer is:
Thin Peroxide Neutralizer
Hydrogen peroxide (35%)5.72
Phosphoric acid (85%)q.s. pH 3-4
Deionized waterq.s. to 100
A variation of this basic cold wave is called a body wave. The same chemicals are used, but the hair is wound on large diameter rods which results in a loose (not tight) wavy curl. This type of treatment may last sixweeks, not three months like a tight curl.
Another variation is the acid perm, a two-part product containing an alkali which is mixed with a low pH reducing agent immediately before applying to the hair. The alkali base can use ammonia to get a pH of 10. When mixed with the acid reducing agent, the final pH is slightly acid, usually about 6.5. The reducing agent is glycerin monothioglycollate (GMT) which is packaged separately because it is not stable when stored with the other perm ingredients. At 6.5, there is little hair swelling so a plastic cap is used under a preheated hair dryer. Since there is no high alkalinity, there is less chance of damaging the hair during the waving cycle and less possibility of skin or scalp damage. There should also be less color removal from tinted hair and the hair should feel more natural. The disadvantage is that the curls are not as tight as an alkaline perm, and they tend to relax sooner.
1. Hillier, N.G.; Profitable Permanent Waving, published by the author, New York, 1948, p 8-9