As a farrier and a blacksmith by trade, I have done extensive research on hand-held forging hammers, as well as hammer techniques and control. My information has come from many different teachers and, of course, many more hours of forging.

Forging is basically applied physics, and physics is a science based on mathematical calculations. When you forge, you are using a hammer to change the form of hot metal with a predictable outcome. When you hit the hot metal in a predetermined way, the metal will change to a form that is determined by the face of the hammer. It’s similar to pressing a hammer head into a piece of clay and then checking the depression that was left.

There are only five basic marks that can be made with a hammer. They are: (Figure1, A through E, respectively) a flat hammer mark or a straight down hit; a left mark or the hammer head tilted to the left; a right mark or tilted to the right; a tilted forward or toe mark; and a tilted back or heel mark. Everything you can do with a forging hammer is a combination of these five marks.

The outcome of the forging process has many variables to consider, such as the size of the hammerhead, the length and size of the handle, and the height and weight of your anvil. Other factors include how you grip the hammer handle…