Steel must be in a soft state (called annealed) in order to form it into the shape of hair scissor blades through hot forging or cold stamping. After all the holes are drilled and the machining processes are finished, the steel blades must be hardened.
The hardening process is called heat treating. The blades are subjected to very high temperatures (up to 2000 degrees F.) for sustained periods together with prescribed cooling off periods. This process transforms the internal molecular structure of the steel to a denser and more uniform state called “martensitic”. Hard particles in the steel called carbides are then very evenly dispersed throughout the steel. This hardened state of the steel is the best for edge holding durability.
It is, however, very brittle and breaks very easily. To add flexibility and strength, the steel scissor blades are subjected to controlled re-heating and cooling, but at much lower temperatures (approximately 400 degrees F.). This procedure is called TEMPERING.
It serves to add toughness and makes the blades more easily sharpened to a keen edge; although it does slightly decrease the hardness at the same time.
Obtaining the optimum balance of hardness and toughness is an art and is subject to many differing opinions. Each manufacture strives to achieve what he feels will be the “perfect hair cutting scissors/shears”. There is, however, no single standard of perfection. Hair Stylists have many individual preferences concerning the feeling and performance of the hair shears.