THE CHOICE OF PERFUMES FOR PRESSURIZED PRODUCTS Where plastic-covered glass containers are utilised, the discolouring effect of light on certain perfume solutions should not be overlooked. H^IR L^CQUERS The original products were based on shellac but, in view of various stability difficulties with the latter, most current formulations consist essentially of polyvinylpyrrolidone or associated co-polymers, dissolved in anhydrous alcohol with appropriate plasticizers, and pressurized with either dichlorodifluoromethane or a mixture of the latter with trichlorofluoromethane The products are usually packed in plain tinplate containers. The possibilities of perfume breakdown under these conditions are con- siderable, and extreme care is needed in their selection and testing. It has been claimed 2• that the replacement of normal trichlorofluoromethane with a grade containing 0.$% nitromethane prevents degradation in hair lacquers and that in its absence 60% of packs develop objectionable odours within two months. Our own experiences by no means support the latter state- merit, where the lacquers are correctly filled and perfumed, and I am certain that many manufacturers will be of the same opinion. However, further experience may prove that the use of the stabilised propellant will reduce the possible hazards and facilitate the development of a wider range of suitable perfumes. The predominant tendency originally was to use only sufficient perfume in hair lacquers to mask the initial and residual odour of the solvent/polymer solutions. The current trend, based on the realisation that the hair is an exceptionally good perfume absorbent, is towards distinctly positive odor- isation especially where the hair lacquer is part of a range of toiletries. Such perfumes must remain pleasing throughout their life on the hair and must not develop stale or cloying effects in the residual stages. Some perfumery materials form complexes with polyvinylpyrrolidone, unbalancing their effect. The plasticizing properties also must be considered carefully results have been reported on the reduction of fihn stiffness caused by certain perfumes, and a method of compensatio• has been described •. Whilst hair lacquers are essentially surface sprays, the user obtains a definite impression from the spray in the air and this must not be overlooked when an assessment is being made. FOAM PRODUCTS Whilst predominantly shaving creams, these include also hand creams, shampoos, cologne foams, etc. The propellant, normally dichlorodifluoro- methane with or without dichlorotetrafluoroethan½, is emulsified in the perfumed product and expels it as a viscous foam. Thus, the effects of atomisation do not have to be considered. Prior experience of the behaviour

396 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS of perfumes in non-pressurized creams and soaps is relevant when supple- mented by careful assessment of the effects of propellants and metallic contamination. Discolouration particularly is to be avoided in order to retain the very pleasing aspect of a pure white foam. Some perfumes affect viscosity, and stability, in emulsions or detract from foaming power. PERSONAL DF. O1)ORANTS The pressure pack is an ideal method of applying these preparations and is assisting in their establishment as toiletries with an accepted place in the hygienic routine. The most popular products are based on G-11, which prevents the bacterial decay of perspiration, and in this way prevents body odours. G-11 freely forms solutions in alcohol which, with the addition of perfume and a small proportion of a non-volatile solvent, followed by pressurization, yield very successful products. In addition to the solubility, corrosion and compatibility aspects, we must consider here specifically the presence of G-11, and the known effects of perspiration on certain perfumery materials. The perfume must cover the initial solvent odour from the spray, giving a light and revitalising effect. Whilst colognes and lighter bouquets remain popular with males, in the case of females there is a trend similar to that described for hair lacquers. The perfume in deodorants is increasingly looked upon as playing an important role in a matching range or as an individual adornment. SUNSCaEEN PaO•)UCTS With the advent of newer active ingredients, such as derivatives of 4-methoxycinnamic acid 2a, possible reactivity is no longer an additional complication in the selection of perfumes. Apart from the obvious factors, we must bear in mind that sunscreening products are applied to large areas of the body which are then exposed to sunlight. The perfume must neither be too overpowering under these conditions nor contain ingredients which, by the influence of sunlight, are known to exert an adverse dermatological effect. HOTJSE•OLD PaO•)UCTS This is a growing miscellaneous field, including starches, for which per- fumes non-discolouring on ironing are required, polishes where the emulsion stability may be critical, spot removers with a solvent odour problem, etc. Masking compounds or positive reodorants are to an increasing extent proving themselves as definite factors in sales appeal.