For spot welding low carbon steel and stainless steel.

Due to the popularity of inexpensive, mass-produced, commercial-grade knives, Damascus steel craft became what many considered a lost art. However, fine quality never really falls out of fashion, and there's no question that Damascus steel is more durable and holds a razor-sharp edge longer than any other steel. Duncan and his colleagues recognized the demand, and they have been largely responsible for bringing Damascus back into vogue.

As the inside of the forge approaches 2,300 degrees, Duncan carefully stacks 10 steel wafers to form a rectangular billet. These wafers are alternating layers of high-carbon and high-nickel steel. He uses an arc welder to attach a steel handle to the rectangle. This also immobilizes the wafers, allowing Duncan to control them during the forging process. Then, like a baker stuffing a loaf of bread dough into an oven, Duncan places the billet into the forge. We pour ourselves a cup of coffee and wait. Within minutes, the billet reaches welding temperature, which is about 2,300 degrees. This is the temperature at which steel molecules separate into a semi-liquid state, allowing them to bond. At this point, the 10 layers will be hot enough to forge into one solid billet.

Duncan removes the billet from the heated forge and puts it under a hydraulic press, which squeezes the layers of steel into one homogeneous mass. He creases the middle of the billet after pressing the layers together and expanding them to the right length. This allows Duncan to fold the billet in half. Now, instead of 10 layers, the billet contains 20 layers. After reheating, he'll fold it again to form 40 layers, then 80, then 160, on up to however many Duncan desires.