When most people think of fountain pens, they think of bottles of ink and filling directly from there. However, sometimes, a bottle of ink is just impractical or inconvenient, like when you are traveling or in school. Therefore, you can also use an ink cartridge to fill your pen.
An ink cartridge is a fully sealed, ink filled container which can be used as a drop-in replacement for the pen's included converter. Only pens that have a removable converter may use cartridges. Thus, piston, aerometric, and vacuum fillers are excluded from using cartridges.
Ink cartridges comes in a variety of different sizes. The two most popular ones are the Standard International Short and Standard International Long cartridges. The Long cartridges hold approximately twice as much ink as the Short cartridges. The Short cartridges will fit almost every pen that accepts Standard International Converters as well as smaller pocket pens like the Kaweco Ice Sport. The Long cartridges will only fit pens with longer bodies and will not fit into pocket pens. Some manufacturers such as Lamy and Pilot opt to use their own proprietary cartridges. If a standard internal cartridge/converter does not fit, then the pen most likely uses a proprietary cartridge.
(From the top: Short Standard International, Long Standard International, Empty Pilot Cartridge, Empty Short International, Empty Long International)
Standard International Cartridges of both sizes can be easily found from a wide range of ink manufacturers like Private Reserve, Waterman, Diamine and J. Herbin. Therefore, you have a wide range of color choices similar to bottled inks. Proprietary ink cartridges are more limited in terms of manufacturer and color. Pilot cartridges will only contain Pilot ink and the same goes for any other maker of proprietary cartridges. Proprietary cartridges may also be refilled with bottled ink, but that is a topic for another post.
If the cartridge you wish to use had a different ink color that you currently are using, be sure to flush the pen first. Mixing two colors can cause some issues with flow and clogs.
To use a cartridge, remove the converter from the pen, if there is one. Most converters can be pulled straight into the pen, or screw counterclockwise.
Next, push a cartridge straight into the section of the pen, where the converter used to fit. You should push the cartridge in as far as you can, and should hear a slight popping sound.
Gently squeeze the cartridge to get ink flow established to the nib. If the pen does not write immediately, leave it nib down for about 2 minutes so ink can flow downwards.
Your pen is now ready to write! To change cartridges, just repeat these steps! You can either toss your cartridges in the trash, or refill them for use again!