•42 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS manufacturing aerosol bottles coated with plastic, and also bottles with plastic coatings tempered in the same way as glass tumblers. Glass bottles are made at high speeds and tempering would make an article very much more expensive. But is it worthwhile for the price involved ? MR. C. BLOOM: Can you give us any information on lightweight bottles ? THE LECTURER: Provided the bottle is well designed and the glass is well distributed, the container will be quite satisfactory with a uniform wall thickness of 0.020". The strongest type of bottle is the round one, which is approximately as wide as it is high square and oval bottles are next in regard of strength, and the rectangular bottle is the weakest. The bottle must be strong enough to withstand contact with other bottles in production and handling. A "multi-point" contact bottle is a much better proposition than a "one-point" contact bottle. The weakest part of a jar or bottle is the bottom half inch. "In-sweeping" of a bottle helps in production. Sharp shoulders should be avoided. Properly designed lightweight containers can be as good as thicker walled bottles. In order to dispense with the re-use of bottles, lightweight containers have been introduced in the United States. As a result, sterilization, etc., is no longer necessary. MR. A. MARSH: Using a semi-automatic process for small runs, is it reasonable to expect and rely on a fully automatic process to produce bottles of the same specification, or are the limits widened on a semi- automatic line ? THE LECTURER: A high speed machine has to be set up with six sets of moulds, and usually a few sample bottles are run off which should be the same as eventual production, but it is very difficult to relate semi- and fully automatic. It depends on the individual factory set-up. Manufac- turers who set up for short production runs would probably use the same machines for bulk production. FLEXIBLE PACKS F. W. NOBLE* Presented at the Symposium on "Packaging in the Cosmetic Industry", organised by the Society at Harrogate, Yorks., on 5th July 1961. The application of flexible films, such as polythene, Pliofilm, etc., to cosmetics, with particular reference to unit packaging of liquid shampoo, and some of the mechanical problems involved are discussed. TH• USE of plastics in packaging has extended very rapidly during the last few years. It is necessary, therefore, to define what we mean by "flexible * Robinson Waxed Paper Co. Ltd., Bristol.

•42 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS manufacturing aerosol bottles coated with plastic, and also bottles with plastic coatings tempered in the same way as glass tumblers. Glass bottles are made at high speeds and tempering would make an article very much more expensive. But is it worthwhile for the price involved ? MR. C. BLOOM: Can you give us any information on lightweight bottles ? THE LECTURER: Provided the bottle is well designed and the glass is well distributed, the container will be quite satisfactory with a uniform wall thickness of 0.020". The strongest type of bottle is the round one, which is approximately as wide as it is high square and oval bottles are next in regard of strength, and the rectangular bottle is the weakest. The bottle must be strong enough to withstand contact with other bottles in production and handling. A "multi-point" contact bottle is a much better proposition than a "one-point" contact bottle. The weakest part of a jar or bottle is the bottom half inch. "In-sweeping" of a bottle helps in production. Sharp shoulders should be avoided. Properly designed lightweight containers can be as good as thicker walled bottles. In order to dispense with the re-use of bottles, lightweight containers have been introduced in the United States. As a result, sterilization, etc., is no longer necessary. MR. A. MARSH: Using a semi-automatic process for small runs, is it reasonable to expect and rely on a fully automatic process to produce bottles of the same specification, or are the limits widened on a semi- automatic line ? THE LECTURER: A high speed machine has to be set up with six sets of moulds, and usually a few sample bottles are run off which should be the same as eventual production, but it is very difficult to relate semi- and fully automatic. It depends on the individual factory set-up. Manufac- turers who set up for short production runs would probably use the same machines for bulk production. FLEXIBLE PACKS F. W. NOBLE* Presented at the Symposium on "Packaging in the Cosmetic Industry", organised by the Society at Harrogate, Yorks., on 5th July 1961. The application of flexible films, such as polythene, Pliofilm, etc., to cosmetics, with particular reference to unit packaging of liquid shampoo, and some of the mechanical problems involved are discussed. TH• USE of plastics in packaging has extended very rapidly during the last few years. It is necessary, therefore, to define what we mean by "flexible * Robinson Waxed Paper Co. Ltd., Bristol.