Bottle caps are a type of closure used to seal the openings of bottles of many types. They can be small circular pieces of metal, usually steel, with plastic backings, and for plastic bottles a plastic cap is used instead. A bottle cap is typically colorfully decorated with the logo of the brand of beverage. Caps can also be plastic, sometimes with a pour spout. Flip-Top caps like Flapper closures provide controlled dispensing of dry products. Bottle caps for plastic bottles are often made of a different type of plastic than the bottle.
Contents |
Bottle caps were originally designed to be pressed over and around the top of a glass bottle to grab a small flange on the bottleneck.
The crown cork was patented by William Painter (inventor) on 2 February 1892 (U.S. Patent 468,258). It originally had 24 teeth and a cork seal with a paper backing to prevent contact between the contents and the metal cap. The current version has 21 teeth. To open these bottles, a bottle opener is generally advised.
The height of the crown cap was reduced and specified in the German standard DIN 6099 in the 1960s. This also defined the "twist-off" crown cap, now widely used in the United States, Canada, and Australia. This bottle cap is pressed around screw threads instead of a flange. Such a bottle cap can be taken off merely by twisting the cap, eliminating the need for the opener.
|
Screw on closures are the most common form of bottle caps. They are easy to apply by a wide variety of automated equipment, or they can be applied by hand. The application torque of closures however must be controlled in order for the closures to perform properly in the field. Closures must be applied tight enough to maintain a seal and to resist closure back-off, but must be not be applied so tightly that the end user cannot remove the closure. A general guide is that the application torque in inches per pound should equal approximately half of the closure millimeter size. As application torque cannot be measured directly on an automatic capper, removal torque measurements are used as an indication of application torque. Since each package will have its own relationship of application to removal torque, the packager should determine this relationship for each of his packages. By applying caps by hand with a torque meter and immediately measuring the removal torque, a correlation between application and removal torque can be determined. This correlation can then be used as an indicator of the actual application torque generated by the capper. By checking removal torque regularly after capping, one can determine if there is a need for adjustment.
Bottle caps are also a way for bottlers to hold promotions, especially for soda companies. A message is printed on the inside of the cap and people with the right message may win a prize. Since the bottle must be purchased to determine the message and win, people usually purchase more of the drink to increase their chances of winning. The most common prize is a free soda from that company.
Some companies, such as Snapple, also print interesting facts on the inside of their caps. Mickey's Malt Liquor as well, prints riddles underneath the 24 and 40 oz. bottle caps. Usually this is done on wide-mouthed bottles that have large caps with enough printing area to put a short sentence.
Bottle caps are, by some, considered a collectible item and some communities like Colnect provide collectors a database to manage their personal collections.