One of the most eco-friendly aspects of owning a fountain pen is the fact that you don't throw away the pen after the ink runs dry. You simply refill it again. How it refills depends on the pen's filling system. To the uninitiated, this might seem daunting. It's like figuring out what part will fix a leaky faucet. Thankfully, it's much easier than that.

Most fountain pens manufactured today use the convenience of the cartridge/converter filling system, giving the writer a choice between installing pre-filled ink cartridges or filling from bottled ink. As you explore different brands of fountain pens, you may encounter different types of filling mechanisms.

In this article, we show you how to identify and fill various modern fountain pen filling mechanisms - from the conventional cartridge/converter to the exotic vacuum filling system.

How to fill a fountain pen with an ink cartridge

A cartridge is a pre-filled, plastic ink capsule. The most common, standard international cartridge, carries about 3/4 of a milliliter of ink. The tapered end has a collar with a protuberance in the center.

  1. The smaller end gets inserted into the pen section.
  2. Once it is pierced, ink begins to flow from the cartridge through the feed, and to the nib by capillary action.
  3. You can wait for the ink to fully saturate the feed or prime the pen by squeezing the attached cartridge.
  4. Once the cartridge is empty, it can be disposed of or refilled with a blunt needle syringe.

With certain pocket-sized pens, the lack of an adaptable converter will force the writer to use cartridges only. In this case, you can use a blunt-tip syringe to refill the cartridge, limiting waste while removing the limitation in ink color variety.

How to fill a fountain pen converter

A converter is like a refillable cartridge. It has the same collar design that attaches to the pen section. The opening fits on the feed post. It utilizes a screw- or pull-action to move the piston inside the chamber.

  1. Make sure the converter is properly attached to the pen's front section.
  2. Move the piston head toward the section by screwing the knob.
  3. Submerge the nib and feed fully into a bottle of fountain pen ink.
  4. Turn the knob in the opposite direction to pull the piston head up.
  5. The suction created by the piston moving from the front-end of the converter to the back will draw up the ink.
  6. Pushing the piston from the back to the front of the converter will force ink, air, or water out of the converter.

The most common converter is the international-style converter, which is offered by several manufacturers. Other pen brands use their own, proprietary converter design that only fits their pens. Lamy, Parker, Sailor, and Pilot are examples of companies that use proprietary converters. To find a complete list of compatible fountain pen cartridges & converters, please check out our Compatibility Guide.

How to fill a fountain pen with a built-in piston mechanism

Before the invention of the cartridge/converter, all fountain pens were "self-filling." The piston mechanism, pioneered by German pen manufacturers in the early 20th Century, remains as the most popular internal filling mechanism for modern pens. Instead of using a removable converter to fill the pen, a piston-filler utilizes the entire barrel of the pen with the blind cap acting as the piston-knob.

Instead of twisting the knob of the converter, the user activates the internal piston by twisting the blind cap on the end of the pen barrel. Modern piston-filling pens tend to be designed to see through with a translucent body or built-in ink window to see the remaining ink in the pen.

How to fill a fountain pen with a vacuum-filling mechanism

This one-stroke filling mechanism operates using air pressure built by the movement of the piston rod. The ink capacity is higher than a typical piston-fill pen and the drawing of the ink is quicker.

  1. To fill, unscrew the blind cap of the pen barrel and pull the piston all the way to the back of the pen.
  2. Fully submerge the nib into a bottle of ink and press the plunger down all the way.
  3. At the very bottom, the air pressure built in the chamber releases and a vacuum causes the ink to flood upward into the pen barrel.
  4. If there is still an air bubble inside the pen, you may repeat the filling steps with the nib submerged in ink.

How to fill an eyedropper fountain pen

One of the oldest pen-filling methods is the eyedropper. Instead of using a mechanism to draw ink into the pen, the user transfers ink into the barrel by means of a syringe or eyedropper. Since the pen barrel lacks a filling mechanism, it has the highest capacity to carry ink

  1. To fill, pour ink into the barrel until the level reaches the inner barrel threads.
  2. Keeping the barrel upright, screw on the section.
  3. It is recommended to apply a small amount of silicone grease to the section threads for a watertight seal.
  4. To help prime the feed, perform the last turn with the nib down, over the bottle of ink or rag.

Pens like the Opus 88 fountain pen are designed to prevent leaking and ink burping with additional o-rings and a shut-off valve. While it is possible to convert some cartridge/converter pens into eyedropper fill, one should do so with great care to ensure the pen will not leak.

Converting fountain pens into an eyedropper-fill pen

Some acrylic resin fountain pens are capable of being converted from a cartridge/converter to an eyedropper-fill fountain pen. A pocket pen like the Kaweco Sport, for example, only accepts an international ink cartridge or the Sport piston converter, which does not contain much ink. If the pen is converted into an eyedropper, the ink capacity is multiplied.

We caution to say that not all cartridge/converter fountain pens can be converted to eyedropper. How to find a good candidate for eyedropper conversion? First, check the inside of the pen barrel and the section threads that attach to the barrel. If there is any metal that would come in contact with the ink, then you can't eyedropper convert it. Most likely, the metal will corrode due to constant ink exposure. Second, you would have to test the barrel to see if it can hold water. Some pen barrels are made in separate parts. They may have a finial that is not completely watertight. Fill the pen up with water and let it sit for a day on a paper towel. If you see leakage, it's a no-go. To verify your own findings, look up your particular pen model and the words "eyedropper conversion" on google to read up on the trials of fellow pen enthusiasts before you.

The key to eyedroppering a fountain pen is using 100% silicone grease. The section threads need a little coating of this grease to create a watertight seal where the section attaches to the barrel. When writing with an eyedroppered pen, be mindful of any drastic changes to air pressure or temperature, especially as the ink level drops below half the total volume of the barrel. Such atmospheric changes can cause air to expand inside the barrel and force out ink through the nib, causing a "burp" of ink on the page as you write.

Other (Vintage) Filling Systems

While the aforementioned methods are the most common filling systems you will find on modern fountain pens, you may stumble across unusual types in vintage pens, such as lever, crescent, vacumatic, safety, snorkel, aerometric, touchdown, and so on. Each has its own unique design, filling instructions, benefits, and drawbacks. If you're interested in vintage fountain pens, we suggest looking for them at a pen show. Talk to the dealer to find out more information about the pen and its filling system.

The type of filling system that best suits you is a decision that weighs convenience versus ink capacity. If you want a high ink capacity and don't switch colors often, then a piston, vac or eyedropper will work well for your writing habits. A writer that lives out of their suitcase might find cartridges more convenient than carrying glass bottles of ink. If you change colors often and have 10 to 20 pens inked at one time, you may like the option of a cartridge converter so your pens do not sit with a full barrel of ink for months at a time.

Filling a fountain pen should not be a hassle. It's one of the fun aspects of owning a refillable writing instrument that will last you decades instead of being thrown in the trash when it runs dry. We hope the information in this article helped you fill your fountain pen or find a filling system that meets your writing preferences. If you have any questions, please feel free to contact us and we'll be glad to help.