Diamine Registrar Ink Cartridges in Blue / Black – Pack of 18

18 Ink Cartridges Per Package. International Size 1 1/2 Long Ink Cartridge Diamine Registrar’s Ink is a waterproof archive-quality blue-black ink color that is an iron-gall based ink. This is a traditional fountain pen ink that is suitable for all makes of fountain pens. Ink can be used by Registrars and Clergy to sign official documents preventing the writing from fading over time. It is recommended that you clean your pen with water prior to refilling or storing your pen after using this ink.