Razor be used on both sides, with two open edges. The blade on the double-edged safety razor is slightly curved to allow for a smoother and cleaner shave. In 1901, the American inventor King Camp Gillette, with the assistance of William Nickerson, patented a new variation of safety razor with disposable blades. Gillette realized that a profit could be made by selling an inexpensive razor with disposable blades. This has been called the razor and blades business model, and has become a very common practice for a wide variety of products. Many other brands of safety razors have come and gone.
American Safety Razor Company building at 333 Jay Street then became the new campus for the Polytechnic Institute of Brooklyn. Seeking diversification Philip Morris acquires American Safety Razor in 1960. In 1963 American Safety Razor is the first maker of stainless steel blades, which were sold under the Personna brand name. In 1968, Philip Morris, purchased the Burma-Vita Company, makers of Burma-Shave. In 1970, the first blade made with tungsten steel was introduced, the Personna 74. In 1974 American Line Brand of industrial products was introduced, expanding the company into industrial blades. In 1977, executives purchased Personna American Safety Razor Company from Philip Morris