Rohrer & Klingner dokumentus, document ink, black, 50 ml Rohrer & Klinger's Dokumentus ink is the world's first certified fountain pen inkfor document useaccording to ISO 12757-2 Tested by the Paper Technology Foundation in Heidenau, it can be used by registrars for official documents Waterproof, non-fading, unerasable and PH-adjusted New technology and high quality natural materials guarantees permanent archival writing Replace the cap of your fountain pen after use to prevent blockages in the nib