The array of different hammers used in jewelry and silversmithing can be rather overwhelming at first, and it is difficult to select the one or two that will be useful and versatile. Hammers have different heads for different purposes: a round, flat-faced head on one end with a round domed or wedge-shaped at the other is the kind of hammer with which most of us are familiar, but there are also rounded rectangular heads, broad, flat heads, wedge-shaped heads, square block heads, round heads, and many more, all made for specific purposes.
One factor that must be considered is the weight of the hammer. A light hammer is used for riveting or hitting a chasing tool, for example. A heavy hammer used for these tasks would be unbalanced and difficult to use evenly. It is important that metal is kept well annealed during all the stages of hammering, except when it is being made springy. If the metal becomes too hard when it is being hammered, it will crack.
A planishing hammer - that is, one with a flat, highly polished face- is used to smooth out marks made by other hammers. The planishing hammer is worked in the same direction as the ordinary hammer.
A planishing hammer or the polished, flat head of a ballpeen hammer is used to stretch, strengthen, and add springiness to rings, bangles, neckpieces, pins, and so on. If a length of wire that is going to be used for a neckpiece needs to be springy, for example, the wire is first annealed and then the whole length is coiled around a section of the mandrel that is a few sizes smaller than the required finished size. It is then hammered around the mandrel as it is gradually pushed down to increase the diameter. By the time the wire has reached the full diameter, it will be springy.
Mallets are either wooden or are made from rawhide or rubber. They are used to shape metal against a metal stake, but because they are relatively soft, they do not mark it. Used on its own, a mallet will not stretch metal nor harden it to any great degree.
The action of the hammer comes from the wrist. The weight of head is balanced against the weight of the handle, so that a rhythmic movement can develop, which makes it possible to hit the metal with blows of equal pressure. Hammer marks left during the making process have to be removed so that the piece has a smooth, shiny finish. The more even the marks are, the more easily they can be removed or smoothed out with a planishing hammer.