From holding bouquets of flowers together to keeping daily newspapers folded or rolled, elastic bands (also called rubber bands) are surely one of the 20th century's most useful and convenient products ever invented. With the multiple industrial, household and other uses that they can be put to, elastic bands have become virtually indispensable items in our daily lives, ever since latex--the rubber tree sap used to produce rubber--was discovered.
While Englishman Thomas Hancock is credited with the creation of the first basic elastic (rubber) band in 1820, his self-developed masticator machine was the forerunner of today's modern, elastic band-manufacturing milling machines. Subsequently, the first elastic bands were patented by Thomas Perry, another Englishman, in 1845.
While it's true that synthetic rubber accounts for approximately 75 percent of all rubber products produced today, organic (natural) rubber is the main ingredient still used for producing elastic bands, as it offers far more elasticity than synthetically produced rubber. However, elastic bands would never be as practical, convenient and useful as they are today had the ancient Mayan People not discovered latex--the milky-white sap they collected from rubber trees--which, apart from being used to produce rubber, gives natural rubber its superior elasticity.
Raw Material / Purification
The production process of elastic bands begins with the procurement of latex, the primary raw material used to produce elastic (rubber) bands. However, prior to packing and shipping, the harvesting, purification and production process of latex is conducted on the rubber plantations themselves.
Purified latex is imported by the United States and other rubber-producing countries from rubber plantations in Asian countries, particularly Indonesia, Malaysia, Sri Lanka and Thailand, and also west coast of Africa.
To obtain latex, a small 2 mm swath is cut into the trunks of full-grown rubber trees every other day. The latex (sap) is collected in cups placed just below the swaths.
Latex is then purified by a straining process to remove all elements other than rubber, as well as filtered to remove debris, tree sap and other impurities.
Following straining and filtering of the latex sap, formic or acetic acid is added to it, and the mixture is then stored in large vats and left to coagulate and dry. During this stage, rubber particles present in the mixture cling together, and, as a result, rubber slabs are formed. Rollers are then used to squeeze out any water or moisture present in the rubber slabs.
Finally, the rubber slabs are pressed into either 2- or 3-square-foot blocks or bales and then packed and shipped to rubber factories or elastic band manufacturers, as the case may be.
Mixing and Milling
In an elastic band-manufacturing factory, the rubber slabs are machine cut by a 1916 Femely H. Banbury-invented machine, called a Banbury mixer. This machine is often used by manufacturers to mix the rubber slabs with other additives--chemicals to increase or decrease elasticity, pigments to give them a particular color and sulfur for vulcanizing them. Although the Banbury mixer delivers a better finished product as it integrates the three additives more efficiently and thoroughly, some companies include these ingredients during the subsequent milling stage.
Milling is the next stage in elastic band production whereby the treated (mixed) rubber slabs are first heated. The resultant molten mass is then flattened in a milling machine.
Extrusion and Curing
After milling, the heated and flattened rubber is machine cut into strips and then passed through an extruding machine. Here, the rubber is put into elongated, hollow tubes.
The hollow rubber tubes are then stretched over talcum powder-covered aluminum poles (referred to as mandrels). The talcum powder prevents the rubber tubes from sticking to the poles. Despite being vulcanized, the rubber tubes may still be brittle during this stage and will therefore need curing. For efficient curing, the mandrels are placed on steamed and heated racks of large (curing) machines.
The final stage of production involves the removal of the rubber tubes from the mandrels. They are then washed or wiped clean of talcum powder and subsequently passed through another machine where they are finally cut into the finished elastic (rubber) bands. The individual weight and width of machine-cut elastic bands can be delivered as per customer-provided specifications.