A leather strop is a surface that is used after the finest stone for the final stage of sharpening. The function of a strop is to polish the edge and work off any burr left behind by sharpening stones. Although other materials are used such as Balsa wood, Nano Cloth and Denim, strops are generally made of leather. Both the suede and smooth sides of the leather can be used. They can be mounted to a rigid base, like leather on a wood paddle strop, or can be flexible like leather or a linen razor strops traditionally used by barbers.
Strops are frequently used with abrasive compounds, the very fine abrasives that give a mirror polish to the edge. If you choose to use a compound, start by applying it to the surface of the strop. A little bit of compound tends to go a long way, so there’s no need to go overboard.
Hold the blade bevel against the surface of the strop with light pressure and move the blade away from the cutting edge. Flip the blade over and do the same on the other side. The process is the same on any stropping medium like Balsa and Nano cloth, with or without a honing compound.
Avoid moving the blade toward the cutting edge as it will cut into the strop surface, resulting in dulling of the edge and cutting into the strop. A few strokes is usually enough to bring the edge back. A strop is best used prior to the edge becoming dull. Used consistently, it is a key step in maintaining a razor sharp edge.
Straight razors are traditionally stropped on a smooth leather. The grain side surface is perfect for the delicate, low angle edges found on straight razors.
Many carvers and knife sharpeners use suede strops. The nap of the suede holds onto compound well, allowing the strop to be loaded easily. The softer surface also provides a bit of rounding to the bevel as the suede compresses under the blade, which some find desirable.
Those who don’t use as much or any compound may prefer the smooth grain side leather. Sharpeners of woodworking tools such as chisels where a rounding of the bevel is not wanted, find that the slightly harder surface works to their advantage as well.