4. FILLING TEST — Fountain pen filling systems: complete guide

Cartridge, converter, piston, or vacuum. Discover how the different filling systems work and which one best suits the way you write.

All fountain pens have one thing in common: they need ink to write. However, the way that ink gets inside them can be completely different.

Some refill in a matter of seconds. Others invite us to pause, open a bottle of ink, and enjoy a small ritual. Some mechanisms can hold a large amount of ink, while others stand out precisely for their simplicity.

Although it may seem like a purely technical detail, the filling system influences our writing experience much more than we think. Because not all of us write as often, use our fountain pen in the same situations, or enjoy the same rituals.

So, which filling system is best? The answer depends on you.

The small ritual of filling a fountain pen

For some people, filling a fountain pen is simply a necessity. The ink runs out, they refill it, and they keep writing.

For others, it's one of the most special moments of using a pen. Opening a bottle of ink, dipping the nib, operating the mechanism, and watching the ink flow into the reservoir. Then carefully wiping the nib before writing again.

It's a process that connects us with the instrument in a different way. And that's exactly where we find one of the big differences between filling systems.

Cartridges: convenience and simplicity

Imagine you're taking notes during a meeting and your fountain pen runs out of ink. With a cartridge system, the solution can be as simple as removing the empty cartridge, inserting a new one, and carrying on writing once the ink starts flowing again.

No need to carry an ink bottle or operate filling mechanisms. This ease of use makes cartridges an especially practical option for those who use their fountain pen on the go, travel often, or simply value convenience.

Many fountain pens from brands like Pilot, Platinum, Lamy, or Cross use cartridge systems, although it's important to remember that not all formats are compatible with each other.

Their main advantage is simplicity. However, the range of colors available depends on the type of cartridge each fountain pen accepts.

And that raises a first question: do you prefer the convenience of changing a cartridge, or are you drawn to the idea of experimenting with countless bottled inks?

Converter: the freedom to choose your ink

What if you could enjoy the versatility of a cartridge fountain pen and, at the same time, the experience of filling it straight from a bottle?

That's where the converter comes in. It's a small refillable reservoir that fits many cartridge-compatible fountain pens and lets you use bottled ink.

Instead of replacing an empty cartridge, you can fill the converter with your favorite ink. Bold blues, deep greens, burgundies, grays, and a huge variety of shades that turn every refill into a chance to experiment.

What's more, many fountain pens let you switch between cartridge and converter depending on your needs, offering versatility without giving up simplicity.

That said, a converter's capacity is usually fairly limited compared with certain built-in filling systems. For those who write many pages a day, this detail can matter.

Piston: when filling with ink is part of the experience

In some fountain pens, the filling mechanism isn't an accessory but part of the instrument itself. That's the case with built-in piston systems.

Instead of using a removable cartridge or converter, they have a mechanism that lets you draw ink directly into the reservoir in the pen's barrel.

To fill it, you usually turn a knob at the end of the barrel, dip the nib into the ink bottle, and operate the piston to draw up the ink.

It's a simple gesture, but there's something special about it: the feeling of using a mechanism designed specifically for that instrument.

The Pelikan Souverän is one of the great benchmarks for this system. Its piston mechanism is part of the identity of a collection that generations of writing enthusiasts have come to know and love.

Its advantages include a generous ink capacity, depending on the model, and the pleasure of using a built-in mechanism. On the other hand, refilling requires an ink bottle and a little more attention than swapping a cartridge.

But maybe that small ritual is exactly what you're looking for.

Vacuum system: the range to keep on writing

Now let's imagine you use your fountain pen for long writing sessions. You take notes, write several pages a day, or simply prefer not to worry too much about when the next refill will be.

In that case, mechanisms with large-capacity reservoirs can be especially appealing.

One of the best-known examples is the Pilot Custom 823, which features a vacuum filling system.

It works differently from a conventional piston. Using a plunger, the mechanism creates a pressure difference that draws ink into the reservoir.

This solution combines engineering, a distinctive filling experience, and a considerable ink capacity. What's more, its translucent versions let you see part of the mechanism and the ink inside.

That said, this system has certain usage and maintenance particularities worth knowing about, such as the need to slightly open the shut-off valve during long writing sessions, following the manufacturer's instructions.

Because more capacity doesn't necessarily mean more convenience for everyone.

Does more capacity mean a better system?

Not necessarily. We tend to think that the more ink a fountain pen can hold, the better. But let's imagine two people.

The first writes several pages every day, always using the same ink. The second enjoys changing colors every few days.

For the first, a large-capacity reservoir can be a huge advantage. For the second, it may be more practical to use a cartridge or a converter that's easy to empty and clean.

Changing inks is part of the fun, too

Some people find their favorite ink and use it for years. Others have a collection of ink bottles that never seems to stop growing.

If you like experimenting with colors, properties, and finishes, you probably especially value how easy it is to change inks.

Every change means emptying and cleaning the system before using a different color. In some fountain pens, this process is very simple, while in others, especially those with more complex mechanisms, it can take a bit more time and care.

That's why choosing a filling system isn't just about thinking how you'll fill it. You should also ask yourself how you want to use it afterward.

Do you prefer to keep experimenting with new inks, or to fill your fountain pen and forget about refilling for as long as possible?

So, which filling system suits you?

Maybe you've never asked yourself this question. Maybe you've always used cartridges for convenience, or maybe you enjoy the ritual of filling a fountain pen as much as the act of writing itself.

Maybe you prefer to change inks constantly. Or maybe you're looking for a reservoir that lets you write for a long time without interruption.

Each of these preferences tells us something about the type of instrument that might suit you.

Because choosing a fountain pen isn't just about deciding how we want it to write, but also about discovering how we want to use it.

FILLING TEST · Discover your ideal filling system

At Pen Week 2026 · The Writing Lab, we want to help you find your writing formula.

That's why we've prepared our Filling Test, an online experience to discover which filling system best suits your preferences.

Are you after speed and convenience? Do you like experimenting with different inks? Do you enjoy the ritual of filling your fountain pen? Or do you prefer the longest possible range?

Through a few simple choices, you'll discover which mechanism suits you and get to know fountain pens you might never have considered.

You don't need any technical knowledge or previous experience. Just think about how you use your fountain pen and what you enjoy most.

Because each system has its own way of approaching writing. And the interesting part is finding the one that best goes with yours.

If you need help, contact us and we'll be happy to help.