JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS LABORATORY EVALUATION OF NEW PACKAGING MATERIALS S. J. PALLING, B.Sc., A.R.I.C., and E. J. MACAREE, M.Inst. Pkg.* Delivered at the Surnmer Conference of the Society on 2$th A•tgust 1960. The materials and methods employed in determining a suitable plastic container •or a cosmetic pack are reviewed. A description o• the materials is given, together with a number o• physical tests which are used to check their l•er•ormance. Problems and techniques involved in package evaluation are also discussed. A I•Ac}•AcE is usually designed to meet t•vo quite different sets of require- ments, the commercial and the technical. The former includes such factors as the appeal to the customer arising from decoration or distinctive shape. It is not the purpose of this paper to discuss such considerations and the associated testing. Most of the technical requirements can be summarized briefly under three headings. 1. The package should effectively contain the product. 2. The package should protect the product from outside influences, and should retain in the package all that is essential to the product. 3. The pack and product must be compatible. The primary object of laboratory evaluation should be to establish the suitability of the package from these points of view, bearing in mind the proposed method of marketing and the standard of quality required. We propose to discuss such testing under two broad headings: Firstly, a description of the materials and problems and secondly, an outline of the methods of testing. l lefore doing so, may we first repeat a request that is often made but very often ignored, to consider the package development at the same time as formula development so far as possible. It may take as long to choose a suitable packing material as to develop a formula. *Research Department, The Metal Box Company Limited, London, W.$

LABORATORY EVALUATION OF NEW PACKAGING MATERIALS The Nature and Use of the Newer Materials }¾[ATERIALS AVAILABLE Regenerated Cellulose has been known and used as a wrapping material for very many years, and nowadays is used either alone or in conjunction with other films in considerable quantities. It may be used plain, or coated with various materials which modify its moisture vapour permeabilities. Cellulose is also used in the form of the acetate. Polyethylene is one of the principal materials of the new packaging era and is being used in ever-increasing quantities. One authorit? gives a figure of 750% increase in production 1952-1959. Here again it may be used as unsupported film, or in combination with other films and coatings. Low, medium and high density polythenes, having different physical proper- ties, are available the common material is the former. (Representative densities of the three groups are 0.910-0.925 0-926-0.940 0'941-0'965.) It is heat sealable, has excellent strength, flexibility and moisture barrier properties, is clear and may be printed. The use of high density polythene may not develop to any great extent for flexible packaging in the cosmetic industry, but there is a very good chance of its increasing use as a bottle blowing material. Pliofilrn. This is rubber hydrochloride and was the first transparent plastic film that could be heat-sealed. It may be used unsupported, and is available in various grades and gauges. For cosmetic purposes it is mainly used in conjunction with other films in the form of laminates. Its water absorption is negligible, and it has high acid and alkali resistance. Since certain essential oils have an effect on Pliofilm, careful tests of tiffs feature should be carried out before deciding to use the material. Another disadvantage is its poor resistance to sunlight. Polyester fihn is typified by Melinex in this country. It has a brilliant clarity, relatively low water vapour permeability, very low gas permeability, and its chemical resistance is good. It withstands a very wide temperature range, but is not easily heat-sealed. It is still in an early stage of develop- ment, and is mostly used at the moment laminated to other fihns, for example Melinex/polythene. Polypropylene. Again a very new material. It can have a high gloss and brilliance and is heat-sealable. In comparison with polythene it exhibits lower gas and odour permeabilities and has good oil resistance. Polypropylene at the present time is being used mostly for bottle-blowing, although some filrn is available. Vegetable and •nineral oils are among the liquids for which the absorption rate is low, even at elevated temper- atures which, with the low odour penetration mentioned, suggests a very useful material for cosmetic products.