However , historical tamahagane was frequently in the range of 3 % to 4.5 % , essentially making it cast iron .
Good tamahagane contains around 1 % of carbon and should not go over 1.5 % .
Historical tamahagane was frequently in the range of 3 % to 4.5 % , essentially making it cast iron .
Good tamahagane contains around 1 % of carbon and should not go over 1.5 % .