Cryogenic Processing of Materials is the technique of immersing materials in liquid nitrogen (at -196 degrees C or -320 degrees F) in order to strengthen them. The cold temperatures cause the molecules to shift into alignments that are less subject to wear. This works with metals, wood, and some plastics. Some web sites simply call this "cryogenics," but that confuses it with the more common and proper definition of the term, which is "a branch of physics which deals with the production and effects of very low temperatures," typically -90 C and below.