Platinum Pen Co. is currently the only company in Japan that manufactures blue-black ink in a classic way.
At first, the dye colour appears, and later the iron in the ink oxidizes and turns black and fixes. The characteristics of this type of ink are that it has a bright color at the beginning of writing and turns black over time. This oxidization process makes the ink highly water resistant and suitable for permanent preservation.
Platinum has paid close attention to the process of changes in the colors of their ‘Classic Ink’ line and have released six new colors with the aim to enhance the joy of using fountain pens. They have placed emphasis on the shading this type of ink provides so the ‘Classic Ink’ line can offer a rich deep writing experience.