PRODUCTION AND PROPERTIES OF GLASS CONTAINERS 15 Tu• LECTURER: I presume you wish me to refer to Araldites and Epikotes in particular. There is a curing range below which a lacquer is under-cured and above which it is over-cured or burnt. The simplest way of testing this is by colour, and our Lacquering Section provides a series of "swatches" which show the limits of the colour of the final film. There is, however, another lengthy and time-consuming way. The film is sprayed with mixed solvents, left to absorb them, swell and then wiped off. The more a lacquer is cured the greater its resistance to mixed solvents, chloroform, methylated spirits, etc., depending on the type of resin used. The colour of the film is, however, a very good guide. MR. R. K. WALMSLE¾: With reference to plastic nozzles, do you not have a problem of protecting an uncut edge somewhere within the seal ? How do you protect the cut edge of the tube which is unlacquered, from the product ? T• L•CTURER: The raw edge of the metal does not come into contact with the product at all and fits into a flange device in the plastic nozzle. The product thus cannot come into contact with the cut edges. MR. R. K. WALMSLE¾: IS the nozzle applied after lacquering ? TUE LECXtJR•R: Yes, and internal waxing is applied after the plastic nozzle is fitted. For that reason we are experimenting with polypropylene because of the temperatures involved in the waxing operation. PRODUCTION AND PROPERTIES OF GLASS CONTAINERS C. TARRANT* Presented at the Symposium on "Packaging in the Cosmetic Industry", organised by the Society at Harrogate, Yorks., on $th July 1961. The historical origin, composition, chemical durability, surface treatment and flaking of glass are discussed. The protection of light sensitive products is also dealt with. •DEFINITION G•-Ass IS so commonplace a part of everyday experience that a definition is almost unnecessary, yet the term has been applied to such a variety of substances that some preliminary indication should be given as to the type of substance the properties of which are to be considered here. * Key Glass Works, Ltd, London S.E.14.

PRODUCTION AND PROPERTIES OF GLASS CONTAINERS 15 Tu• LECTURER: I presume you wish me to refer to Araldites and Epikotes in particular. There is a curing range below which a lacquer is under-cured and above which it is over-cured or burnt. The simplest way of testing this is by colour, and our Lacquering Section provides a series of "swatches" which show the limits of the colour of the final film. There is, however, another lengthy and time-consuming way. The film is sprayed with mixed solvents, left to absorb them, swell and then wiped off. The more a lacquer is cured the greater its resistance to mixed solvents, chloroform, methylated spirits, etc., depending on the type of resin used. The colour of the film is, however, a very good guide. MR. R. K. WALMSLE¾: With reference to plastic nozzles, do you not have a problem of protecting an uncut edge somewhere within the seal ? How do you protect the cut edge of the tube which is unlacquered, from the product ? T• L•CTURER: The raw edge of the metal does not come into contact with the product at all and fits into a flange device in the plastic nozzle. The product thus cannot come into contact with the cut edges. MR. R. K. WALMSLE¾: IS the nozzle applied after lacquering ? TUE LECXtJR•R: Yes, and internal waxing is applied after the plastic nozzle is fitted. For that reason we are experimenting with polypropylene because of the temperatures involved in the waxing operation. PRODUCTION AND PROPERTIES OF GLASS CONTAINERS C. TARRANT* Presented at the Symposium on "Packaging in the Cosmetic Industry", organised by the Society at Harrogate, Yorks., on $th July 1961. The historical origin, composition, chemical durability, surface treatment and flaking of glass are discussed. The protection of light sensitive products is also dealt with. •DEFINITION G•-Ass IS so commonplace a part of everyday experience that a definition is almost unnecessary, yet the term has been applied to such a variety of substances that some preliminary indication should be given as to the type of substance the properties of which are to be considered here. * Key Glass Works, Ltd, London S.E.14.