A strop is a length of material, usually leather or cotton, used to realign the edge before shaving.
Types
Hanging strops
The most common type of strop is the hanging strop. Usually made of leather or cotton it is a long rectangle of material. One end of the strop is hung from a hook or something else, while the other end is held and pulled taut with a hand.
Hanging strops come in different widths from about 50mm (2") to about 75mm (3"). A 50mm wide strop requires you to do definite long X type laps when stropping. A 65mm wide strop does not require you to do such definite long X type laps while a 75mm wide strop allows you to do straight laps up and down. The wider the strop, the more susceptible it is over time to cupping. A strop of about 65mm width is a good compromise.
Strops also vary in length from a stropping length of about 300mm (12") to 600mm (24") or more. The shorter the stropping length, the more laps are needed for the same effect on the blade's edge. The longer the strop, the difficult it can be to use. A good compromise is a stropping length of about 450mm (18").
Hanging strops come in different widths from about 50mm (2") to about 75mm (3"). A 50mm wide strop requires you to do definite long X type laps when stropping. A 65mm wide strop does not require you to do such definite long X type laps while a 75mm wide strop allows you to do straight laps up and down. The wider the strop, the more susceptible it is over time to cupping. A strop of about 65mm width is a good compromise.
Strops also vary in length from a stropping length of about 300mm (12") to 600mm (24") or more. The shorter the stropping length, the more laps are needed for the same effect on the blade's edge. The longer the strop, the difficult it can be to use. A good compromise is a stropping length of about 450mm (18").
Paddle strops
Comes in a variety of sizes. Its main advantage is its use while traveling. Easily stored in luggage for long or short trips. Typically shorter than the hanging strop. There is no need to create tension as it is inheritanly built-in which creates somewhat of an advantage for the beginner by removing this variable. Paddle strops can be two-sided or four-sided. Can have various leathers attached or wool felts for applying abrasives. Commonly used after honing to refine the edge with diamond or chromium oxide pastes.
Loom strops
Materials
Leather
The most common, and most used, material for strops is leather. Leather provides a soft and smooth surface which gently aligns the edge of a straight razor. It is only used in both hanging and paddle strops.
Textile
The textile type of strop is often called linen, but few modern strops use actual linen. The most common material used is cotton. It is only used in hanging strops, not paddle strops.
Balsa
Balsa wood is sometimes used on paddle strops instead of leather.
Synthetic
The introduction of synthetic materials are now available. Some synthetics are made of nylon web core with a thermal polyurethane covering bonded to the core. Due to the material being non-pourous, it is not suited for use in a pasted paddle strop.