A razor strop is a strip of material, usually leather or canvas, used to straighten and sharpen the edge of a straight razor, knife or other cutting tool. Unlike honing, which requires the use of a sharpening stone, a razor strop does not remove material from the blade but merely re-aligns the edge to restore its cutting acuity. Strops are used to polish the metal blade and remove burrs left over from honing, and a variety of polishing compounds may be used in conjunction with the strop to achieve the desired level of finish. The best known type of razor strop is the hanging strop, but there are also hand-held, paddle versions available.
Razor strops are not a commonly used item in the early 21st century, because safety razors and fancier knife-sharpening devices have made them somewhat dated. Stropping is still considered one of the best ways to achieve a fine, polished edge to any cutting blade, according to those who prefer a straight edge to a disposable razor. Any implement with a cutting edge — such as knives and various woodworking tools — may benefit from stropping, but the nature of the straight razor particularly lends itself to the technique. The carbon steel used in many razors is soft and, though the stainless steel used in other razors is harder, the thinness of the blade lends itself to stropping, which doesn't remove any material the way grinding does.
The two materials used in razor strops are canvas and leather, with the former being the more abrasive. After honing, a cutting edge is sometimes stropped on a canvas surface first, and then polished on a leather strop. Various grades of abrasive pastes may be used with either razor strop, and many experts recommend ending with red jeweler's paste on the leather strop to ensure the finest edge and highest level of polish. For straight razors, especially, the type of paste used may differ according to the composition of the blade, and diamond pastes are sometimes favored because they work better on the harder steel being used in contemporary straight razors.
Aficionados of straight-edge razors claim the microscopic changes that occur in the razor's edge with use tend to "grow" after the razor has been put away, stretching the formerly fine edge out of alignment and dulling its surface. To maintain the edge necessary for the perfect shave, the implement must be stropped after just a few shaves, with some experts recommending stropping before each use. Most sources agree that using a razor strop more, rather than less, will extend the life of the blade and reduce the need for grinding or honing.