THE JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS This edition is published for THE SOCIETY OF COSMETIC CHEMISTS OF GREAT BRITAIN by Pergamon Press, Ltd., Headington Hill Hall, Oxford Editorial Office: Ashbourne House, Alberon Gardens, London, N.W.11. ¸ 1963 Society of Cosmetic Chemists of Great Britain VOL. XIV OCTOBER 1963 10 HAIR LACQUER SYSTEMS AND THEIR EVALUATION R. C. HARRIS* Presented at the Symposium on "Aerosols", organised by the Society, at Southport, Lancs., on &tth April 1963. The various ing•dients, propellants, valves and containers, used for aerosol hair lacquers and the general principles of formulation in all its aspects are discussed, as are water-based aerosol hair lacquer systems. Typical formulations are given, and methods of laboratory evaluation and their 11mitatious are discussed. Reference is made to the problems of toxicity and fi•.mm•_bility. HAIR SETTING lotions based on water-soluble gums of vegetable origin have been used for many years, but the rapid-drying hair lacquer is a comparatively recent development. Its use was fairly limited until the advent of the aerosol pack which provided a simple and efficient means of applying this type of product. The aerosol hair lacquer first appeared in the U.S.A.. in 1949, and today, in most countries, its sales exceed those of any other type of pressurized product. However, currently in several countries, the innocuity of the inhaled lacquer spray is being questioned and the flammability characteristics of hair lacquers (and other products) are being investigated critically, so any consideration of hair lacquer systems must pay due attention to these aspects. *Swallowfield Aerosols Ltd., Wellington, Somerset. 469

470 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS The conventional pressurized hair lacquer consists basically of an "anhydrous" alcoholic solution of a fihn former, together with a chloro- fluorohydrocarbon propellant system, whereas the so-called water-based product, now appearing in significant numbers, employs an aqueous alcohol as the solvent and a hydrocarbon propellant system. In both types, other ingredients such as auxihary solvents, plasticizers, perfumes, corrosion inhibitors, "conditioning" agents and spirit denaturants may be included. The composition of the "concentrate", i.e. the solution of film former and other ingredients, the type of propellant system, the ratio of propellant to concentrate, and the type of valve used, are the four critical factors which together determine the performance of the complete hair lacquer. The hair lacquer is a surface coating product and whilst some formulation and laboratory evaluation problems are similar to those encountered with paints, there is one significant difference--the substrate to which the hair lacquer is applied. Not only do the natural characteristics of hair vary considerably from individual to individual, but the hairs may also be damaged or modified by bleaching, permanent waving, or by the use of rinses. The hair shafts vary in thickness and have an irregular surface "lubricated" with sebum, which is a varying mixture of fats, fatty acids, hydrocarbons, sterols, inorganic and organic salts. Apart from these varying properties of the substrate, none of which would commend themselves to a paint technologist, there is also the problem created by the ultimate user. The lacquer will be sprayed from varying distances despite explicit instructions on the dispenser, and, similarly, the quantity applied will vary sharply. It is not surprising, therefore, that laboratory evaluation of hair lacquers must be supplemented by user trials despite their limitations. LAgORATORY EVALUATION There are a number of factors governing the efficacy of hair lacquer which can be evaluated in the laboratory. These procedures can be used for quality control purposes, and for the initial screening and comparison of new formulations. Tests on locks of hair give valuable information, particularly regarding ease of combing and the tendency to flaking or stripping of the lacquer film. The primary purpose of a hair lacquer is to hold the hair in the desired position, which is achieved by the stiffening effect of the film former which will be modified by the presence of other ingredients such as plasticizers, perfumes, lanolin derivatives, etc., and also by the humidity of the atmos- phere. The stiffness or holding properties of the hair lacquer may be checked by several methods. Switches of hair which have been set into curls by water, dried and then sprayed, can be suspended in a controlled