CURRENT TRENDS IN COSMETIC PRESSURE PACKS 405 'such as PVP/VA, are simply diluted forms of PVP and therefore also covered. So far as is known, no similar application for a patent has been filed in this country. A number of alternative resins have been developed, .and although samples of some are at the moment only available in the U.S.A., in due course they will no doubt also find acceptance over here. An alternative to PVP and the copolymers of vinyl pyrrolidone and vinyl acetate P(VP/VA) which suffer from the fault that they take up too much moisture in a humid atmosphere, is the use of polyvinyl imidazole (PVI) 5. The lacquer obtained is claimed to yield a film which is said to •be substantially tack-free at relative humidities of 50% to 00%. This new resin is soluble in water and also in alcohol. The pressurized formula- tion is covered by a patent ø. From tests described it is noted that mixtures •f PVP and PVI are less hygroscopic than PVP/VA copolymers in the 'same proportions. It is not necessary to include a plasticiser or special .detackifying agent in pressurized hair lacquers based on this resin. Alcohol is needed as a solvent when utilizing propellants 11 and 12, in which 11 makes up 20-25•o of the mixture. PVI is soluble in ch!orotrifluoroethane, and if this relatively new propellant (Arcton 155a) were to be used then an .alcohol-free spray could be prepared. Another alternative would be the use of polymers of substituted N-vinyl •)xazolidinones 5'7. For pressurized hair sprays PVO-E is suggested and this is poly-N-vinyl-5-ethyl-2-oxazolidinone. Yet another alternative is PVO-M (Devlex 180) in which the ethyl group has been replaced by methyl. Details of hair setting preparations based on these resins are found else- where 8. PVO-E has the advantage of being more soluble in alcohol- propellant mixtures than PVO-M. It is, however, less soluble in water, and might not wash out of the hair very easily. At the moment PVO-E is not produced commercially. A copolymer of PVO-M and PVA is marketed as Devlex A515. This copolymer is more compatible with organic solvents than PVO-M, but it is not very soluble in alcohol-propellant mixtures. In order to prepare a satisfactory pressurized lacquer from Devlex A5lg, it _/s necessary to make use of cosolvents such as methyl chloroform ,(Chlorothene), or methylene chloride •. Altogether the number of patents dealing with hair spray compositions ß ,•0,n is on the increase, particularly in the U.S.A., and marketers will (lo well to ascertain that their intended formulations cause no patent infringements. The trend to market tinted hair lacquers is also on the increase and recently a range of temporary hair colours was announced by a British firm •. This particular range is available in shades of pastel pink, lilac, black, pastel blue, auburn, chestnut brown, gold, smoky grey, and green. There would also appear to be considerable scope for expanding the

406 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS sale of hair preparations for men. One British firm is already producing a hair lacquer, but no hair creams have yet been marketed in this country. A well-known hair dressing has been marketed only quite recently in the U.S.A., though in the unconventional piston-type of pressure container •a. Although somewhat more expensive than the conventional container, it does offer the possibility of keeping the propellant and product apart, where such separation is considered necessary. In some European countries, brilliantine is now being marketed in the conventional pressure pack, i.e. with fluorocarbon propellant. One particular product is available either with a standard valve or with a metering valve, though for both types a mechanical break-up spray actuator is employed •. Geary's work on low cost water based pressure packs could also have a tremendous influence on future expansion of pressurized hair lacquers. According to Geary •5, a satisfactory spray can be obtained when using as little as 14% Ucon 12. It is, however, necessary to ensure that the corrosion inhibitor, which may turn out to be the most satisfactory from a functional' point of view, has no deleterious effects on the performance of the lacquer. DENTAL CREAM The sales of dental cream, both in the U.S.A. and in the U.K., continue to decline. In the U.S.A., as will be noted from Table 2, there is a decrease of over 70% in total units sold from 1959 to 1960, and even if one assumes that all dental cream sold was packed in 12 oz. dispensers then there is still at least a 50% decrease in total weight of dental cream. In this country, the total sales of pressure packed toothpaste probably never exceeded 1 million units, and the sales are also declining despite the recent introduction, by a multiple store, of its own new brand •ø. Pressure packed toothpaste is one of the few products where the packing principles involved offer no specific advantage over the conventional collapsible tube,. and this underlines the fact that a successful pressure pack must offer at least one distinct advantage over conventional packing, be it ease of appli- cation, convenience of handling, a.s.o. That is not to say that nitrogen- propelled packs have no future quite the contrary, as will be discussed below. COLOGNES AND PERFUMES No one can fail to be impressed by the substantial increase in the one- ounce-and-under cologne and perfume group, as revealed by Table 2. Although glass containers have increased to a greater extent than metal containers, many of the former are in fact protected by metallic outers, and very handsome looking packs they do indeed all turn out to be. No one in this country has yet managed to reproduce the elegance of the many