What is clay tempering, and which tachi pieces in this collection feature it?
Updated Mar 2026
Clay tempering is a heat-treatment technique in which a mixture of clay is applied along the spine and flat of the blade before the quench, leaving only the edge area exposed. During the rapid quench in water or oil, the uncoated edge cools faster and achieves greater hardness, while the clay-insulated spine cools more slowly, remaining tougher and more flexible. The result is a blade with a visible hamon - the wavy or straight line separating the harder edge from the softer body - which is one of the most prized visual features in Japanese sword collecting. The clay tempered 1095 carbon steel tachi with teal ito wrap in this collection explicitly undergoes this process, producing a blade with both authentic structural character and strong display appeal.