What types of ink are safe to use in fountain pens?

To ensure smooth writing performance and to protect your pen’s delicate feed and nib, always use inks specifically formulated for fountain pens. These inks are carefully balanced in terms of viscosity, pH, and chemical composition to work with the fine capillary action within your pen. Inks intended for other purposes—such as India ink, calligraphy inks, or drawing inks—often contain pigments, particulate matter, or thickeners that may clog the feed or even damage the nib over time. Reputable brands design their inks for fountain pen use, so sticking with these products that are clearly labeled “fountain pen ink) is the safest choice.