Fountain Pen Filling Systems Explained

Fountain Pen Filling Systems Explained

Choosing a fountain pen begins with choosing an appropriate ink-filling system. There are several ways to get ink into a fountain pen. In this post, we cover the most popular methods and weigh the advantages and disadvantages of each method.

JetPens Primer Video: Fountain Pen Filling Systems

In this JetPens Primer video, we give a general overview of the most common filling methods for fountain pens.

In the text below, we discuss each filling system in more extensive detail and list the different products that were used in the video.


A cartridge is a small reservoir of ink, usually coming in tube form. This system makes ink filling easy.

Cartridge Fountain Pen

1. To install a cartridge, begin by inserting the cartridge’s stopper into the fountain pen’s grip section.

Cartridge Fountain Pen

2. Press the cartridge down firmly into the fountain pen’s grip section until the cartridge stopper is punctured.

Cartidge Fountain Pen

3. Leave the pen pointing downward to help the ink saturate into the nib. This step can take an hour or two.

Products Used

  • Kaweco Classic Sport Fountain Pen – Extra Fine Nib – Clear Body
  • Kaweco Royal Blue Ink

Advantages of Cartridges

  • Cartridges are the simplest way to fill fountain pens with ink. They come preloaded with ink, making it easy to pop in a new cartridge with ease.
  • Cartridges are lightweight, which makes them more convenient and portable than converters and built-in filling systems, where bottled ink is necessary.
  • Among the systems covered in this post, they tend to be the least expensive.

Disadvantages of Cartridges

  • Many fountain pen brands use proprietary cartridges that are incompatible with pens from other brands, which limits color choice.
  • Cartridges don’t allow the use of the wide range of inks in bottled ink form. However, it’s possible to work around this drawback by using a blunt-tipped syringe to refill a spent cartridge with bottled ink.
  • Cartridges have less ink capacity than other filling systems since they are separate components from the barrel.

Cartridge with Converter

A converter uses mechanical force to create a low air pressure chamber into which ink is drawn. Begin installing a converter the same way that you would install an ink cartridge. Dip the pen into a bottle of fountain pen ink until the nib and part of the grip section is submerged in the ink.

There are two types of converters: piston converters, which use a twist mechanism to draw ink, and squeeze converters, which use a simple press mechanism to draw ink. Below, we explain how to install each type of converter.

1. Piston Converter

Piston Converter Fountain Pen

1. Insert the converter into the pen and twist the end knob until the piston is fully extended.

Piston Converter Fountain Pen

2. Twist the piston in the other direction, retracting to draw ink. Repeat if the converter is not full.

Piston Converter Fountain Pen

3. Clean up by wiping off the nib with a paper towel and reassemble the fountain pen.

Products Used

  • Pilot Con-50 Fountain Pen Converter
  • Pilot Penmanship Fountain Pen with Ergo Grip – Extra Fine Nib – Clear Body
  • Sailor Jentle Yama-dori Ink (Copper Pheasant) – Four Seasons – 50 ml Bottle

2. Squeeze Converter

Squeeze Converter Fountain Pen

1. After inserting the converter, squeeze it. Bubbles will appear in the ink bottle as air leaves the converter.

Squeeze Converter Fountain Pen

2. Release the converter slowly and as you do so, the difference in air pressure will cause the ink to be drawn into the pen.

Squeeze Converter Fountain Pen

3. Squeeze and release again, repeating until no bubbles appear in the bottle when the converter is squeezed.

Products Used

  • Pilot Fountain Pen CON-20 Fountain Pen Converter
  • Pilot Penmanship Fountain Pen with Ergo Grip – Extra Fine Nib – Clear Body
  • Sailor Jentle Yama-dori Ink (Copper Pheasant) – Four Seasons – 50 ml Bottle

Advantages of Converters

  • Many cartridge pens are also compatible with converters.
  • Converters give cartridge pens access to the wide variety of bottled inks.

Disadvantages of Converters

  • Not all converters are interchangeable. Converters sometimes use proprietary designs so it’s important to check converter and fountain pen compatibility.
  • Because they are separate components much smaller than the pen barrel, converters have a smaller ink capacity than built-in filling system pens or eyedropper convertible pens—many converters only hold half as much ink as a cartridge.

Fountain Pen with Built-In Filling System

Rather than requiring a separate converter or cartridge, some fountain pens already have a filling system built in them, which allows writers to fill them straight from a bottle. There are two types of built-in filling system fountain pens—piston and vacuum.

1. Built-In Piston Filling System

Built-In Piston Fountain Pen

1. To use a pen with a built-in piston, begin by submerging the entire nib into the ink bottle.

Built-In Piston Fountain Pen

2. Continue by twisting the end knob of the fountain pen until the piston is fully extended.

Built-In Piston Fountain Pen

3. Twist the knob in the other direction, retracting the piston and drawing ink into the pen.

Products Used

  • TWSBI ECO Black Fountain Pen – Extra Fine Nib
  • Sailor Jentle Yama-dori Ink (Copper Pheasant) – Four Seasons – 50 ml Bottle

2. Built-In Vacuum Filling System

Built-In Vacuum Fountain Pen

1. To fill a vacuum fountain pen, begin by unscrewing the knob at the end of the pen and pull back the plunger.

Built-In Vacuum Fountain Pen

2. Push the plunger back down. This gesture creates a low air pressure environment in the ink chamber behind it.

Built-In Vacuum Fountain Pen

3. Once the plunger reaches the flared part of the ink chamber, the air pressure difference causes the ink to rush into the pen.

Products Used

  • TWSBI Vac700 Fountain Pen – Broad Nib – Clear
  • Sailor Jentle Yama-dori Ink (Copper Pheasant) – Four Seasons – 50 ml Bottle

Advantages of Built-In Filling Systems

  • Fountain pens with a built-in filling system have a much larger ink capacity than a comparably sized cartridge or converter filled fountain pen since the entire pen barrel can contain ink.
  • Fill the fountain pen straight from the bottle and choose from the endless variety of different inks that exist in bottled form.

Disadvantages of Built-In Filling Systems

  • Fountain pens with built-in filling systems tend to be more expensive than fountain pens that use converters or cartridges.
  • Fountain pens with built-in systems can’t be used with ink cartridges, so it’s necessary to have access to bottled ink.

Eyedropper Pen

An eyedropper pen is one whose barrel is filled with ink using an eyedropper, syringe, or pipette. Many of the earliest fountain pens were designed as eyedropper pens and could not be filled any other way. Nowadays, most eyedropper pens are actually cartridge fountain pens that have been converted into eyedropper pens for the sake of increasing their ink capacity.

Squeeze the converter. Bubbles will appear in the ink bottle as air leaves the converter.

1. For the eyedropper method, begin by unscrewing the fountain pen barrel.

Eyedropper Convertible Fountain Pen

2. Coat the threads of the grip section with silicone grease to ensure a watertight seal.

Eyedropper Convertible Fountain Pen

3. Fill the barrel with ink up to the threads of the grip section, then reassemble the pen.

Products Used

  • Pilot Petit1 Mini Fountain Pen – Fine Nib – Baby Pink
  • Diamine Pink Ink – 30 ml bottle

Advantages of Eyedropper Pens

  • Eyedropper pens typically have a very large ink capacity because no space is wasted on separate components.
  • It’s possible to choose from a variety of different color inks using the eyedropper method.

Disadvantages of Eyedropper Pens

  • Not all cartridge fountain pens are suitable for eyedropper conversion—the pen barrel must be airtight and there should not be any exposed metal on the inside of the barrel.
  • Filling the fountain pen with the eyedropper method is leak-prone since the entire barrel of the pen is filled with ink rather than separate components.
  • The eyedropper method is less convenient and portable than a cartridge or a converter because it requires a variety of different materials, including bottled ink, silicone grease, and eyedroppers.


Assembling ink into a fountain pen can be intimidating, but once you understand the basics of fountain pen filling systems, falling in love with this timeless stationery icon is inevitable. Let us know in the comments below what your favorite ink filling system is and why.

Mechanism Convenience Capacity Price
Cartridge High Medium Low
Converter (Piston and Squeeze) High Low Low
Built-In Piston Medium High Medium
Built-In Vacuum Medium High High
Eyedropper Convertible Low High Low