If a chisel is going to be used for mortising or other work where it will be driven with a mallet the upper end of it should be protected from the mallet by a leather washer or a metal ferrule. Such a chisel should have a handle of durable wood such as beech, hard maple, ash, osage or some exotic such as bubinga or purple heart. These chisels are called "firmer chisels" or "firmer gouges." A chisel is flat in section, and a gouge is "U" shaped. The steel in the flat ones comes in two shapes; square edged or bevel edged. The square ones are generally somewhat heavier and stronger. Both kinds are attached to their handles in one of two ways; with a socket or with a tang. The socket chisel is the stronger of the two and would be the choice for heavy work, a socket chisel has a tapered socket on the top end and the handle is tapered to fit into this socket. A tanged firmer chisel or gouge has a wide flat backed place called a bolster built into the tang and a long tapered point that gets fitted into the end of the handle. The bolster butts up against the end of the handle and prevents the tang from being driven any further into the handle. Tanged chisel handles have a metal ferrule where the bolster joins the handle to protect the handle from splitting. I tend to favor bevel edged firmers, they are more delicate, lighter, and can be fitted into corners more easily. If I am not intending to drive them with a mallet, and plan to use them for light and careful paring work I will want a handle that is just nicely rounded wood on the upper end. This will be easy on my palm when I am pushing it into the wood. If I am going to drive it with a mallet I will want the leather cap or a metal ring on the top of the handle. I use a turned maple or beech mallet for driving them because the round shape will cause it to glance off to the side, missing my hand, when it does not strike the end of the handle squarely. Both maple and beech are tough hard woods that can take repeated pounding, and both make good mallets. Firmer chisels and gouges come in various lengths, the longer ones enable working farther away from the edge of things or working in deeper mortises. They both come in a style called "crank neck" in which the tang, between the bolster and the blade, is bent twice so as to offset the blade from the handle. This lets the tool be used flat on the work without interference from either the handle or the worker’s hands. Both straight and crank neck gouges are sharpened either "in cannel" or "out cannel". "In cannel" refers to a gouge ground on the inside surface of the U shaped blade, and "out cannel" refers to one ground on the outside surface.