<P> The basic form of a razor, "the cutting blade of which is at right angles with the handle, and resembles somewhat the form of a common hoe", was first described in a patent application in 1847 by William S. Henson . This also covered a "comb tooth guard or protector" which could be attached both to the hoe form and to a conventional straight razor . </P> <P> The first attested use of the term "safety razor" is in a patent application for "new and useful improvements in Safety - Razors", filed in May 1880 by Fredrik and Otto Kampfe of Brooklyn, New York, and issued the following month . This differed from the Henson design in distancing the blade from the handle by interposing, "a hollow metallic blade - holder having a preferably removable handle and a flat plate in front, to which the blade is attached by clips and a pivoted catch, said plate having bars or teeth at its lower edge, and the lower plate having an opening, for the purpose set forth", which is, to "insure a smooth bearing for the plate upon the skin, while the teeth or bars will yield sufficiently to allow the razor to sever the hair without danger of cutting the skin ." The Kampfe Brothers produced razors under their own name following the 1880 patent and improved the design in a series of subsequent patents . These models were manufactured under the "Star Safety Razor" brand . </P> <P> A third pivotal innovation was a safety razor using a disposable double - edge blade that King Camp Gillette submitted a patent application for in 1901 and was granted in 1904 . The success of Gillette's invention was largely a result of his having been awarded a contract to supply the American troops in World War I with double - edge safety razors as part of their standard field kits (delivering a total of 3.5 million razors and 32 million blades for them). The returning soldiers were permitted to keep that part of their equipment and therefore easily retained their new shaving habits . The subsequent consumer demand for replacement blades put the shaving industry on course toward its present form with Gillette as a dominant force . Prior to the introduction of the disposable blade, users of safety razors still needed to strop and hone the edges of their blades . These are not trivial skills (honing frequently being left to a professional) and remained a barrier to the ubiquitous adopting of the be your own barber ideal . </P> <P> The first safety razors used a single - edge blade that was essentially a 4 cm long segment of a straight razor . A flat blade that could be used alternately with this "wedge" was first illustrated in a patent issued in 1878, serving as a close prototype for the single - edge blade in its present form . New single - edge razors were developed and used side - by - side with double - edge razors for decades . The largest manufacturers were the American Safety Razor Company with its "Ever - Ready" series, and the Gem Cutlery Company with its "Gem" models . Although single - edge razors are no longer in production they are readily available . Blades for them are still being manufactured both for shaving and technical purposes . </P>

When was the double edged safety razor invented