Clay and Tempering

Putting the clay on the blade. The shape of the clay determines the hamon style. In this example, the hamon is a "gunome".

The clay is dried on a heater before tempering. The thickness of the clay is adjusted using a file - a layer either too thick or too thin can affect the tempering result.

The blade is heated up to bright orange colour in fire. The temperature of the blade must be even throughout the whole length.

The red-hot blade is quenched in water. The clay-covered part cools down slower, forming the flexible back; the part with no clay cools down quicker, forming the rigid cutting edge.

This is the result after tempering. The hamon is barely visible at this stage, but will slowly reveal itself during the following polishing work.