DEVELOPMENT OF MACHINELESS PERMANENT WAVING 185 means and method which today are known as "machineless" pads used and the "machineless method" of permanent waving of hair. The term "machineless" aptly describes the system because for the first time women were emancipated from wires and overhanging sup- ports. As with many basic inventions, in retrospection and upon casual examination it appears to be simple and obvious. Primarily Winkel's invention (U.S. Patent No. 2,051,063) in- volved the use of a single moisture- absorbent element to accomplish the following functions: (1) to supply the water to initiate and continue the exothermic chemical reaction (2) to serve as a wet shield to prevent the hair from being damaged by being heated to a high dry heat (3) to serve as a fast heat conductant to the wound hair strand since the element lay be- tween the hair and the envelope containing the exothermic heat. The second element of Winkel's invention involved the use of a flex- ible impervious envelope, one face of which was perforated. Thus the water was pressed through the per- foration to the chemical. The heat generated was quickly transferred by the wet element to the hair, thus raising its temperature almost as fast as the temperature within the pad. The impervious envelope by permitting the steam to issue in only one direction allowed for only little heat to escape by radiation except in the direction of the hair. What heat was not used, as with a small swatch of hair, escaped as steam, but the wet absorbent, serv- ing as the water giving means and the system depending upon water for exothermic reaction, became an automatic control to assure that no overheating to a dry state occurred. The very high efficiency of this unit allowed for a marked decrease in the amount of heat required-- the Winkel pad requiring only 12 gm. of lime, while the Sartory sys- tem required about three times this amount (actually 35 gm.). The Winkel pad was not a perfect pad even though it was used com- mercially, but Evans and his co- workers immediately saw with their background of experience with the Sartory set-up that here was the opening to the blind alley. Sales AfFiliates, Evans' company, bought the Winkel invention, and Evans started an intensive research pro- gram to improve the product. The first of the improvements was the overcoming of one of the major limitations of the Winkel pad. This was the lack of an assured and standard control over the generation of the heat by the exothermic chemi- cal reaction. Evans was the first to recognize that this could be done chemically and Patents 1,892,426, 1,894,032, and 1,919,690 were issued to him. In the very first stages of work on the Winkel machineless pad, it was recognized by Evans and McDon- ough that other exothermic chemi- cal reactions would better serve to generate the heat than the hydra-

186 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS tion of lime, which Winkel's patent mentions as a suitable example of exothermic'reaction. Among the many reactions studied, the oxidation-reduction type of reaction involving the oxi- dation of a metal like aluminum with an oxidizer like a chlorate offered the most possibilities. The explosive violence with which alumi- num combined with an oxidizer to generate a very intense heat and high temperature had been put to use in the metal thermit welding units of Goldschmidt. ' A1 -{- Fe20• --• A120• -{- Fe -{- A How to control this type of reaction became the subject of a research program, giving rise to the invention specified in the Evans and McDon- ough patent U.S. No. Re 22,660. In this research .program it was found that the reaction must involve an electron transfer through a solu- tion means rather than a direct combination of materials. Even with this type of reaction the re- action can either be so slow as to generate no perceptible heat or so violent that the steam development will drive out all the water and will generate temperatures giving rise to direct combination which, of course, results in heat of the intensity of bombs. Means for smoothing out the electron transfers therefore became a problem which was solved through (1) the use of materials to control the hydrogen ion, particularly at the start of the reaction, and (2) the inclusion of materials which would give rise in the reaction mixture to catalysts for example, a nascent metallic element like copper, which would assist the aluminum metal in the loss of electron and a metallic ion like the cuptic ion which would assist the chlorate ion in the accept- ance of the electron. The inclusion of an absorbent material within the mixture is a necessity not only to give body to the water solution but also to pre- vent spontaneous combustion which might result from direct combina- tion of the reducing a•ent and oxidizing agent if only they were mixed together and subjected to high storage temperatures on mechanical attrition. Compositions utilizing the oxida- tion of a metal like aluminum to generate heat for the permanent waving of hair have been disclosed in the Racen U.S. Patent 2,183,587 and Reed's U.S. Patent 2,208,815. The impervious perforable en- velope of Winkel was made of aluminum foil, and so far no better substitute material has been found, even though during the war numer- ous substitutes had to be resorted to. The element carrying the water in Winkel's original pad was flannel, and .while he specified that it must be adapted to be wet with a liquid and that it must give up through the perforation a part of the liquid to the exothermic mixture, never- theless, the flannels were a source of trouble. This was due to the fact that it was hard to get flannel having the standard properties for speedy