Steel Material of Clay Tempered Katanas

The Smith, or the Sword maker, proceeds by preparing the Tamahagne, a material block made of several layers of steel with different carbon tenors. The Tamahagne is obtained through a smelting process: Folding and
welding layers of carbon steel; the process allows getting the impurities out of the materials and result in clean steel block.

Generally, 1095 carbon steel  is the most adequate for making Clay Tempered Katana. While the other Carbon Steel types are not really being used. The difference is in the Clay mixture that applies in each type of steel and it is certainly the role of the smith to determine the combination. Traditionally, several layers of carbon steel of different Carbon tenors are folded together to obtain a primary material on which the smith will apply the process of clay coating.

Clay Application Process

The previous operation, which is folding and welding Steel layers, gives also the “billet shape” to the resulting worked steel. The smith proceeds then to clay application to start the real making of Clay Tempered Katana. The process consists in covering the blade with some layers of wet clay mixture. This mixture is prepared according specific proportions that each smith keeps to himself, but it is generally a compound of Clay, water, stone powder, and rusts and may be some ash. The clay slurry is applied differentially to the edge and the spine of the blade; the edge being destined to be sharpened later. The clay application is done while heating the material, then hammered and quenching in water or in oil according to the smith. This differential clay application and the quenching operation result in hardening the edge of the blade and keep the spine relatively soft.

Clay Tempered Katana Forging

Clay Tempered Katanas are therefore generally made of carbon steel blade professionally and differentially coated with Clay slurry to obtain a differential hardness along the blade. The differential hardening process allows the sword to acquire the beautiful curves, usually ordered by users and clients. Repetitive heating and quenching –sudden cooling in water- allows the material to go through several Steel phases which are known to be advanced forms, solid and hard. The process of heating-quenching uncovers the structure of Hamon, the line downside the blade. It is important to make it more clearly through the polishing process which comes later. It is important to notice that the processes of preparing the Steel material and Clay slurry application are particular and the smith should know what proportions to use to obtain certain characteristics of the sword such as the Hamon structure and the blade curve, and the Tang properties as well. You can then order the shape, the hardness and the Hamon of the blade, and the smith will choose the adequate combination to make your wish come true.