Explains Everything on Instagram: "To fill a fountain pen with ink, you'll need to understand its filling mechanism. There are four main types: Cartridge, Converter, Piston, and Vacuum. For a C Vacuum pen, unscrew the mechanism cap, pull the plunger all the way out, and submerge the nib into the ink bottle. Then, slowly push the plunger back in to fill the barrel with ink. Wipe excess ink away from around the section and nib with a paper towel. For a Piston pen, submerge the nib in the ink bottl