Bottle cap

Metal caps with plastic backing are used for glass bottles, sometimes wrapped in decorative foil.

Caps were originally designed to be pressed over and around the top of a glass bottle to grab a small flange on the bottleneck.

It had 24 teeth and a cork seal with a paper backing to prevent contact between the contents and the metal cap.

The "flip-top", "swing-top" or "Grolsch" style consists of a plastic or ceramic stopper held in place by a set of wires.

Prior to the invention of the crown cork, this was the dominant method of sealing bottles that contained carbonated liquid.

In the European Union, the 2021 EU directive on "tethered caps" demands that screw caps of PET beverage bottles under 3 litres (including composite containers, i.e. carton) will have to be afixed to the bottles starting July 2024 in order to reduce waste and improve recycling.

F217 has become the industry standard due to its all-purpose compatibility, resilient, compressible seal, cleanliness (no pulp dust) and economy.

Plastisol is the standard lining material used in metal closures for vacuum packing glass bottles and jars.

Molded in Low-Density Polyethylene, Polyseal cone liners form to the inside of the bottleneck providing a leakproof seal which guards against back-off and product evaporation.

The design typically features a 0.045” molded inner flange which when applied with normal application torque compresses to approximately one-half of its thickness while sealing against the bottle lip.

This style linerless mechanism is available in popular dispensing caps and has the advantage of being simpler & cheaper to manufacture.

One of the more prominent uses of the conventional metal bottle cap in popular culture is its use in the Fallout series of video games.