This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
This is a simple, thin, flat disk, of specially prepared rubber packing, with a tasteless, impervious facing on the side next to the beverage. It is made of considerably larger diameter than the mouth of the bottle, and forced into it in convex shape, seating itself in a groove near the top of the bottle, where it remains, requiring no fastener to hold it, yet capable, within itself, as it is claimed, of resisting an internal pressure of over 100 lbs. per square inch on account of the arched form, an arch being self-sustaining. The seal is provided with a strong central stud, by which it is easily and quickly extracted. The plain stud seal, for present use beverages, is faced with shellac varnish. For high-grade carbonated goods, mineral waters, steamed beer, and all goods that remain long bottled, the seal is faced with pure tin foil, free of lead, or with a special protecting substance. It is claimed that these foil seals are absolutely tasteless, no matter how long the goods may be bottled. Both the shellac-faced and the foil-faced seals are also without studs; they are extracted with a common corkscrew, or a special opener. The bottling machine for carbonated beverages employed in conjunction with this bottle seal is illustrated on another page. This is the only rubber stopper yet introduced that, like cork, is used but once. The seal being extracted, the bottles can be washed with any of the bottle-washing machines.
Fig. 299. - Sectional View of Bottle Seal.