Cartridge, converter or piston: filling systems explained simply

It may seem like a small decision… until you end up with ink-stained fingers, the ink doesn’t flow the way you expected, or you realize that refilling your pen can be the most satisfying moment of the day. The filling system is not a technical detail: it’s what turns your fountain pen into a routine… or into a ritual. And once you understand it, everything falls into place—comfort, cleanliness, autonomy, and even the type of ink you’ll enjoy using.

In this guide, we explain—without complications—the three most common ways to “feed” a fountain pen: cartridge, converter, and piston. You’ll see the advantages of each one, who they’re best suited for, and what you should consider to get it right from day one.

Before choosing: what are you looking for in your fountain pen?

Think about your real use. Not the ideal one. The honest one.

• If you write at the office or in class: you’ll probably want speed and zero hassle.
• If you enjoy trying inks and colors: you’ll want the freedom to use bottled inks.
• If you write a lot and don’t want to refill often: autonomy matters.

With that compass in mind, let’s go system by system.

1) Cartridge: “plug and write”

A cartridge is a pre-filled ink capsule. You insert it, it clicks into place, and your fountain pen is ready to go. It’s the cleanest and fastest system—perfect if you want to write without learning anything else.

Advantages of cartridges

• Total convenience: ideal for beginners or for carrying in a bag.
• Clean: almost no risk of getting ink on your hands.
• Fast: changing a cartridge takes seconds.

Drawbacks of cartridges

• Less variety: you’re limited to the colors available in cartridge format.
• Limited capacity: they usually run out faster than other systems (depending on model and cartridge size).
• Compatibility: some brands use proprietary cartridges (not all are universal).

If you’re just starting out, a pen like the Lamy Safari or entry-level models from Pelikan make the cartridge system easy, straightforward, and very rewarding.

2) Converter: freedom to choose any ink

A converter is like a “refillable cartridge.” It fits into the pen just like a cartridge, but instead of coming pre-filled, you fill it yourself from a bottle. It’s the perfect middle ground: convenience on the outside, an endless world on the inside.

Advantages of converters

• Access to bottled inks: this is where the magic begins (for example, Diamine inks and their special shades).
• More sustainable: fewer disposables.
• Easy to clean: you can rinse and change inks without too much effort.

Drawbacks of converters

• Requires a bit of practice: filling from a bottle takes some technique.
• Medium capacity: usually holds less ink than an integrated piston system.
• Variable quality: a good converter makes a difference—sealing, smoothness, durability.

This system is ideal if you’re drawn to the world of colors and want your fountain pen to be a creative object as well. At Iguana, you’ll find many converter-compatible pens, from practical options to more special pieces (such as certain versions of the Pilot Capless, depending on compatibility).

3) Piston: the “true” ritual (and maximum autonomy)

When a fountain pen uses a piston filling system, the pen body itself becomes the ink reservoir. There’s no cartridge or converter—the internal mechanism “draws” ink directly from the bottle. It’s a classic, elegant, and deeply satisfying system.

Advantages of the piston system

• Large ink capacity: perfect if you write a lot or don’t want to refill often.
• Premium experience: filling a piston pen feels like a small mechanical ritual.
• Clean aesthetics: fewer “intermediate” parts inside the pen.

Drawbacks of the piston system

• More maintenance: thorough cleaning can take more time.
• Less plug & play: you’ll always need bottled ink.
• More technical if something goes wrong: as an integrated mechanism, it needs proper care.

In heritage brands like Pelikan (think of ranges such as the Pelikan M200 and similar models), the piston system is part of their identity: autonomy, smoothness, and the feeling of a tool built to last.

Which one should you choose? A quick decision based on your style

1. Choose cartridges if you want ease, cleanliness, and quick refills.
2. Choose a converter if you want to explore bottled inks and change colors often.
3. Choose a piston if you write a lot, want maximum capacity, and enjoy the ritual.

Final tip: your first system doesn’t have to be your last

Many people start with cartridges for convenience, move on to converters out of curiosity… and end up falling in love with piston systems once they discover the pleasure of slow, deliberate refilling. It’s not a mandatory path, but it’s a common one: each system teaches you a different way to enjoy your fountain pen.

If you’d like, the Iguana team can help you choose based on your use, your handwriting, and the type of ink you want to explore. Because when the filling system truly fits you, writing changes: it becomes smoother, more personal… and far more addictive.

Have questions? Want a personalized recommendation? Contact us and we’ll be happy to help