More Crud: Mold
To a chemist, the aniline dyes used in fountain pen inks are organic in nature, and the very presence of these dyes in ink can give rise to mold because to mold they look like food. Mold spores are everywhere around us; every time a bottle of ink is opened, some spores find their way from the atmosphere into the ink. Inks contain chemicals to inhibit mold growth, but not all inks contain enough mold inhibitor.