JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS In contrast to waxes, many resins are soluble in polar solvents. Relatively few resins are compatible with waxes. ThermopIastics .' They differ from waxes principally by their usually much greater molecular weight, higher melting-point, greater toughness, lower crystallinity, and super- ior temperature stability. Solubility in fat-solvents often is, even at a raised temperature, technologically insufficient to some extent the same is true also with regard to certain waxes. Concerning the order of the melting point, there are also high-melting waxes (chiefly •f the amide type, ignoring metal- soap-containing compositions), but they are lacking the plastics' requirements. WAXES V. RELATED MATERIALS The preceding definitions also summarise the salient differences between waxes and "related materials." So far as the cosmetic industry is concerned, representatives of both groups have to satisfy the following requirements, namely' they must be harmless, free from unpleasant or strong odour, and colourless or light-coloured ß they must not cause irritation of the skin they must have no deleterious effect on perfumes or medicating additives, and no tendency to turn rancid' they should act as stiffening agents, and/or as a basis for ointments, or serve as emulsifying agents (as such or in conjunction with mild alkalis, soap, or the like), or as modifying agents (e.g., for texture) in certain cases, such as lip-sticks, hair creams, etc., gloss-effect is required (but this is caused by the fatty materials used, rather than by the waxes) most of the materials concerned possess, at least to some extent, emollient action. The principal waxes used for the manufacture of cosmetics are :- beeswax (yellow and bleached), paraffin waxes, microcrystalline waxes, petrolatums (waxes, besides petroleum jelly) ' to a lesser extent (at least as a rule), the following waxes are used ß spermaceti, 136

WAX AND THE COSMETIC CHEMIST carnauba wax (chiefly yellow and bleached), candelilla wax, ozokerites (yellow or white), "ceresines," and various synthetic waxes. Reference must be made to the fact that refined ozokerites are nowadays often blends of microcrystalline waxes (and/or petrolatums of the hard or the plastic types) with paraffin waxes. Genuine ozokerites are hardly available even in pre-war days they contained large proportions of paraffin wax. Ceresines are, as a rule, hardened and/or opacified paraffin waxes and of no greater technological value than paraffin wax. Bleached carnauba waxes often contain 75 per cent or more of added paraffin wax. The principal "related materials" concerned are: stearic acid (double and triple pressed), stearyl and cety] alcohols (and sometimes others), "Lanette wax SX" (sulphated lauryl alcohol), "Lanbritol wax N21" (in principle, a non-ionic fatty alcohol-poly- oxyethylene ether of optimum chain-length), "Opal wax," "Castorwax" (hydrogenated castor oil), hydrogenated coconut oil, cottonseed oil, etc., wool wax (i.e., wool fat alcohol) and its esters, monoesters of glycerol (GMS), and of ,various glycols (ethylene, propy- lene, diethylene glycols, etc.), diesters of pentaerythritol, Carbowaxes (polyethylene glycols), polyoxyethylene-fatty acid esters, Spans (sorbitan-f•tty acid partial-esters) Tweens (polyoxyethylene ethers of sorbitan-fatty acid partial-esters), Polawax, Cetomacrogol 1000, Aerosols, andother proprietary brands. Practically all the materials listed above are rn. ore or less waxy in appear- ance some of them are called waxes by their manufacturers. (The ranges of Carbowaxes, Spans and Tweens also include liquid products.) Probably with the exception of Opal wax and the other types of hydro- genated vegetable oils, which primarily serve as stiffening additives, they are used (as such, or appropriately combined, or in conjunction with soaps or alkalis), as emulsifying, wetting or spreading agents. Carbowaxes act chiefly as thickeners and aqueous lubricants. Obviously as these materials are completely lacking wax properties they fall outside the wax definition. On the other hand, they have to be men- 'rioned in a discussion of waxes for various reasons. In the definition of wax, emulsifiability is not listed as an essential requirement. This can be easily understood by referring to the fact that 137