Knife making is the process of manufacturing a knife by any one or a combination of processes: stock removal, forging to shape, welded lamination or investment cast. Typical metals used come from the carbon steel, tool, or stainless steel families. Primitive knives have been made from bronze, copper, brass, iron, obsidian, and flint. Materials for blades Different steels are suited to different applications. There is a trade off between hardness, toughness, edge retention, corrosion resistance, and achievable sharpness. Some examples of blade material and their relative trade offs: The newest powder metallurgy steels can be made very hard, but can quickly wear out abrasives and tooling. A blade made from low carbon or mild steel would be inexpensive to produce and of poor quality. A low carbon blade would be very hard to break, but would bend easily and be too soft to hold an edge. High carbon (or high alloy, in some listings) can take a much higher hardness but must be tempered carefully after heat treatment to avoid brittleness. Unusual non-metallic materials may also be used; manufacturing techniques are quite different from metal: The natural volcanic glass obsidian can achieve a nearly molecular edge (high achievable sharpness) and only requires Stone Age technology to work, but is so brittle that it cannot maintain that sharpness for very long. Also the entire blade is very easy to break by accident. Obsidian is used to make extremely sharp surgical scalpels. Ceramic knives hold their edge for a long time, but are brittle. Blade making process Initial forging The initial shaping of a knife is done through forging or blanking. Steel can be folded either to form decorative pattern welded steel or to refine raw steel, or as the Japanese call it, tamahagane. Grain size is kept at a minimum as grain growth can happen quite easily if the blade material is overheated. In a mass production environment, or in a well equipped private shop, the blanking process is used to make "blade blanks." This can be achieved by a number of different methods, depending upon the thickness of the material and the alloy content of steel to be cut. Thinner cross section, lower alloy blanks can be stamped from sheet material. Materials that are more difficult to work with, or jobs that require higher production volume, can be accomplished with water jet cutters, lasers or electron beam cutting. These two