Tape used for electrical applications needs special properties. Not only must it conduct electricity, and be fire safe, but it should also be flexible, easy to tear and be long-lasting.
Electrical tape is typically black, but it is also produced in various colors. Electricians have started using the different colors to help identify voltage levels or different phases of wires such as green indicates an earth ground wire, while blue indicates low voltage.
Although some electrical tape is made from plastic, it is predominantly made from vinyl. Vinyl tape tears easily, stretches and lasts a long time. Stretching is important as it is often wrapped around exposed wires to form a tight seal, protecting the wires from moisture.
Not long after electricity first lit up the world, along came the electrician with the need for tape to complete the job. Early electrical tape was created by coating cotton in tar and using a vulcanized rubber adhesive. The tape rotted fairly quickly and it wasn't strong. The tape was applied over rubber tape for insulating purposes. It was also known to cause corrosion.
Another product came on the market in the early 1940s that would change the inadequate electrical tape problem: vinyl.
In the 1940s, vinyl plastic was emerging as a useful medium for many products. Vinyl worked very well for products like shower curtains, but trying to bond it with an adhesive to make tape had some serious shortcomings.
Vinyl was made with an ingredient called tricresyl phosphate (TCP). This material caused vinyl to have an oily layer. Various types of adhesives were tried in combination with vinyl to form electrical tape, but they all broke down.
3M was put to the task of developing a tape that met the requirements for electrical applications. It wasn't until 1946 that three inventors, Eastwood, Oace and Snell of 3M found the right combination. The basic combination that finally worked was a plasticizer with the vinyl. They also used a nonsulfur rubber adhesive. This combination proved to be the most commercially viable.
The first electrical tape wasn't black though, it was yellow and later white. The white tape created problems when exposed to ultraviolet light, which led to the well-known black tape.
The main component of electrical tape is vinyl, which is made of two main ingredients: chlorine from salt and ethylene from natural gas. Vinyl can be produced in rigid form for products like PVC pipes, semi-liquid or flexible. The flexible version is the basis for electrical tape.
The plasticizer needed to make electrical tape work is a chemical compound called esters. Many types of esters have been created for specific uses. Plasticizers soften the resin, which allow for specialized processing. The resin and the plasticizer do not bind chemically but are held together by an electromotive force.
Electrical tape has become much more versatile than its intended use on wiring projects. It is used by homeowners for many purposes and is found tucked away in toolboxes and junk drawers around the world.