Like other raincoats, a rubber raincoat traditionally is worn over other layers of clothing to protect them, and the person beneath, from rain. As an overcoat, a raincoat even can be worn over other coats that provide more warmth, because raincoats generally are made of a fairly thin material to provide easy storage and transportation. Like other overcoats, a rubber raincoat generally is longer than the average coat and hangs down to about the mid-thigh area in order to cover additional areas of the body during a rainstorm. A rubber raincoat is made out of fabric that has been rubberized, a process that makes the fabric waterproof and rain repellent. Since its invention, the rubber raincoat often is referred to as a Mackintosh, in reference to Charles Mackintosh, a British chemist who first patented waterproof cloth in 1823.
Charles Mackintosh's purpose in creating rubberized fabric was to create a product that would help people cope with Britain's often-rainy weather. He originally tested the idea by using coal-tar naptha to melt rubber into thin sheets, which he then laminated onto wool fabric. The initial models of rubber-coated wool proved to be heavy, stiff and uncomfortable. In addition, the rubber often would melt in hot weather. The many problems of early Mackintoshes were countered by the discovery of the process of vulcanization by Thomas Hancock in 1843.
Vulcanization is a process that converts rubber into a sturdier material by adding sulfur or other chemicals to it during the melting process in order to cure it. Hancock's patent of vulcanization solved the problem of melting rubber. The problems of comfort and stiffness and the lack of portability of early raincoats, however, were not solved until manufacturers started using lighter materials in the production of rubber raincoats later in the 19th century.
Throughout the 20th century, Mackintosh-type coats have been produced using cotton and other light fabrics that make them more comfortable, lighter and easier to transport. The rubberizing process also has been perfected to make the coating much thinner and more durable. Manufacturers also apply solution and/or tape to the seams of the rubber raincoat in order to further seal the coat against possible spots where rain could leak through the coat. All of these processes make the coats stronger while also making them more flexible, which allows for them to be folded and kept in all varieties of bags so that they can be on hand anytime a rainstorm might occur.