PIGMENTS, LAKES AND DYESTUFFS IN COSMETICS 15 NAIL POLISHES These preparations may be described as fine dispersions of colour in a base containing nitrocellulose, synthetic resins, plasticisers and solvents. The original types of formulation were clear and called for dyestuffs in varying shades of red which were soluble in the solvents used. About twenty years ago the cream type lacquer, so familiar to-day, was introduced using pig- mentary colours and titanium dioxide. The primary requirements of a colour in a medium of this type is freedom from bleed. The powerful action of the solvents employed render lakes unsuitable and pigments require very careful selection for this product. The light fastness of the pigment is not of great importance but the colour should have good dispersion qualities and freedom from migratory effects in the liquid polish and in the lacquer film. An associated problem with nail polishes is caused by uneven settling out of the coloured and white pigments on standing which results in a white deposit at the base of the container. This can be overcome by the manufacture of a pigment on a base of titanium oxide which will settle out as a coloured layer and is easily brought back into suspension. It is of interest to note that this can only be effected during manufacture of the particular pigment and cannot be carried out by processing of the colour and the white in the polish base. COLOURS IN SOLVENTS SUCH AS WATER, ALCOHOL, OIL, ETC. This group includes all preparations which involve essentially the colour- ing of a solution by means of a soluble dyestuff. The light fastness of these products is affected by a variety of factors, the most important being pH and perfume and without knowledge of the materials employed it is imposs- ible to guarantee the suitability of any particular type of dyestuff. Diffi- culties are also experienced with thioglycollates, certain cationic surface- active agents and some aluminium salts, and when the range of colours available is restricted by legislation the final choice might not be the ideal required. COSMETIC COLOUR LEGISLATION When considering the statutory control of colours in cosmetics, a matter which concerns all cosmetic manufacturers to a greater or lesser degree, it is of interest to note that only two countries in the world have so far included in their legislation specific and detailed regulations governing the use of colours in cosmetics. These two countries are Canada and the United States of America, and it xvould be well to consider the U.S.A. first of all.

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Legislation in the U.S.A. originated in the Federal Food and Drug Act of 100• when it was laid down that only permitted colours should be used in food and seven coal-tar colours were then specified for this purpose. After ten years, one more colour was added to this list, and even after thirty years from the commencement of control only eight more coal-tar colours had been added to the original list which still applied only to foodstuffs. In 1038 the "Food, Drug and Cosmetic Act" was passed which is the basis of present-day legislation and governs not only the use of colours but any chemical product which may be consumed or applied to the human body. The Food, Drug & Cosmetic Act of 1938 laid down a total number of 11• permitted coal-tar colours or, as they are usually called, "certified" colours, and divided them into three classes: F.D. • C. colours. Colours permitted for use in foods, drugs and cosmetics. D. © C. colours. Colours permitted for use in drugs and cosmetics. External D. • C. colours. Colours permitted for use in externally applied drugs and cosmetics, the lips and any body surface covered by mucous membrane being specifically excluded. Each listed colour was described by accepted scientific terms and a speci- fication for purity laid down in the following manner: 1. Each certified colour section, that is F.D. & C., D. & C. and Ext. D. & C. has a maximum limit for Pb, As and heavy metal content. 2. In the case of barium, certain salts of which are permitted in the D. & C. and Ext. D. & C. sections, a limit is laid down for soluble barium (in dil. HC1) as barium chloride. 3. A detailed specification is given for each individual permitted colour which lists upper or lower limits for pure dye content, water-soluble or insoluble matter, free intermediate content, etc. It is probably not so widely known that the colour must be free from all impurities to the extent that these can be avoided by good manufacturing practice (this can lead to arguments with the Food & Drug Administration-- the ball being very much in the F. & D.A. court). The Food, Drug & Cos- metic Act, as outlined so far, applies only to coal-tar dyestuffs and pigment dyestuffs. Lakes are included as derivatives of permitted colours, but the Food, Drug & Cosmetic Act lays down the base or substratum which are permitted and the radicles, basic or acidic, which may be used as precipitants. A general specification is laid down for each section of the permitted lake colours (for cosmetic colours the specification is the same and covers ether extracts, soluble salts and intermediates). A standard method of nomen- clature is also laid down for these lakes which states that their name shall