Today in 1943, US Patent 2325309 A was issued, an invention of Jan De Swart, for his “Process of Capping Bottles.” There’s no Abstract, although in the description it includes these claims:

This invention has to do with sealing caps for bottles and the like, as well as bottle sealing methods.

In its more particular contemplates a hard and substantially non-flexible plastic cap which is so constructed, of a plastic capable of being rendered temporarily pliable and remolded, as to be applied in sealing relationship to a bottle without injury to the cap and which not only is capable of sealing the bottle against substantial pressures but which also compensates for the cold flow characteristics prevalent in most plastics.

I am aware that attempts have been made to produce a successful thermoplastic bottle cap but so far as I am aware, no such cap has been produced which is capable of general use to cap bottles containing fluids such as carbonated beverages, beer or the like. Such prior caps have been incapable of maintaining an effective seal where substantial pressures are generated in the bottle; and have been incapable of withstanding the temperatures incident to pasteurization processes. For instance, pasteurization processes commonly utilize temperatures of the order of 160 produced do not maintain a seal under such conditions. Another shortcoming of prior caps has been the fact that they fail to maintain an effective seal after the plastics of which the caps are made have undergone the normal cold flow.

It is among the aims of my invention to overcome those shortcomings and, generally speaking, I accomplish this by providing a cap preformed of a cold-setting plastic capable of being rendered temporarily pliable and then reformed and re-hardened about the neck of a bottle. An important characteristic of my improved cap resides in the fact that its side Wall presents a peripheral bead of relatively thick cross-section and having a. relatively low setting rate which, after being temporarily softened, is remolded to aspects, my invention the contour of the external marginal bead forming a part of the conventional beer or carbonated beverage bottle. This bead portion undergoes cap into sealing relationship with the neck or more and thermoplastic caps heretofore l the provision of a plastic cap having a construction which provides a double seal.

Another object is the provision of a cap having a guiding formation to guide it onto a bottle during capping.