Traditionally, Carbon Steel is obtained by firing up a particular type of charcoal within a Clay Tub for approximately 72 hours. Iron powder should be added at determined amounts to associate appropriate quantity of Carbon. At the end, the obtained Steel is Stainless; its solidity depends on the amount of Carbon that associates to Iron. The steel obtained is referred to by four digits number which designates Carbon by the two first digits and the percentage of Carbon within the steel. Thus, 1045 Carbon steel refers to Carbon steel material that contains 0.45% Carbon fraction. It is called Medium Carbon Steel as well because that carbon concentration is the minimal required for the Steel to be used for industrial purposes; there are lower concentrations of carbon, but the materials are not suited for industrial use. 1045 Carbon Steel is suited for making katanas because it is cheaper than the other materials used for this industry. It is softer and easily forged. The proper application of the hardening techniques and the Clay treatment, certainly produce amazing steel that can be forged in real pieces of arts.