Filling a fountain pen is one of those things that looks more complicated than it is. The first time can feel uncertain — ink, mechanisms, the possibility of making a mess — but after two or three fills it becomes entirely natural, the small ritual that is part of what makes fountain pen writing feel different from reaching for a ballpoint.
There are several ways to fill a fountain pen, depending on the pen you have. This guide covers all of them, in plain language, with step-by-step instructions for each. Find your filling system in the contents below and go straight to that section if you'd rather not read the whole thing.
Contents
- Cartridges — the simplest option
- Converters — the door to bottled ink
- Piston fillers — maximum capacity
- Vacuum fillers — the clever alternative
- Eyedroppers — for the maximalists
- How to know which system your pen uses
- What ink can I use?
How to know which filling system your pen uses
If you're not sure, the quickest way to find out is to look at the pen itself. Unscrew the barrel from the section (the part you hold) — this is nearly always how fountain pens come apart. If there's a small plastic tube inside, that's a cartridge. If there's a mechanism with a knob or a squeeze bar, that's a converter. If the pen doesn't come apart this way and has a knob at the end of the barrel, it's almost certainly a piston or vacuum filler. If the barrel is hollow with no mechanism inside, it may be an eyedropper pen.
You can also check the product page on The Journal Shop website, or simply contact us — we're happy to confirm.
Cartridges
Cartridges are the simplest way to fill a fountain pen. A cartridge is a small sealed tube of ink — you push it into the pen, it pierces itself, and ink begins flowing to the nib. No bottles, no mess, no technique required. This is how most people start with fountain pens, and for good reason.
Step by step: filling with a cartridge
- Uncap the pen and unscrew the grip section from the barrel — the part that contains the nib and feed. The cartridge fits into the open end of this section, on the side away from the nib.
- Find the correct end of the cartridge — it will have a small opening, sometimes with a metal ball inside as a seal. This end goes into the pen.
- Push the cartridge in firmly until you feel it click or puncture. It takes more force than you might expect. Don't be timid — a half-seated cartridge won't flow.
- Screw the barrel back on, cap the pen, and leave it nib-down (or on its side) for at least fifteen minutes — and ideally longer. Ink needs time to travel down through the feed to the nib. Don't be surprised if nothing happens immediately; give it time.
- Try a few test scribbles on scrap paper. If ink doesn't flow, re-cap and wait a little longer. For a brand new pen, it can occasionally take an hour for ink to fully reach the nib.
One important thing: cartridges are not universal. Some pens use Standard International cartridges, which fit a wide range of brands. Others use proprietary cartridges that only fit their own pens — Lamy, Pilot, Platinum, Sailor, and Kaweco all use their own formats. Always check before buying cartridges for a pen you don't yet have cartridges for.
Storing a half-used cartridge
If you want to remove a cartridge before it's empty — to try a new ink, or to clean the pen — hold the pen nib-up as you pull the cartridge out, to prevent dripping. The cartridge opening is small enough that surface tension usually keeps the ink in place for a short while, but seal it with a small piece of tape and store it in a zip-lock bag to keep it fresh. Label it if you won't remember which ink it is. A cartridge stored properly this way will keep for two or three weeks; for longer, a small blob of low-temperature hot glue over the opening creates an indefinite seal that peels off cleanly when you're ready to use it again.
Converters
A converter fits where a cartridge would go but connects to a bottled ink — you draw the ink in yourself, through the nib, using a small piston or squeeze mechanism. This is the step that opens up the full world of fountain pen inks: hundreds of colours from dozens of brands, including the extraordinary Japanese inks from Pilot, Sailor, and Kyoto Ink that you can explore on The Journal Shop.
Like cartridges, converters are often brand-specific. A Lamy converter fits only Lamy pens; a Pilot converter fits Pilot pens. The good news is that converters are inexpensive, reusable indefinitely, and stocked by The Journal Shop for all the major brands we carry.
Step by step: filling with a piston converter
Piston converters are the most common type — a small knob at one end operates an internal piston that draws ink in.
- Insert the converter into the pen's section, in place of the cartridge. It should click or fit snugly.
- Twist the knob to push the piston all the way down, expelling any air. Do this before dipping in the ink to prevent splashing.
- Dip the nib into the ink bottle. The entire nib and feed should be submerged — not just the tip. This ensures a good seal and a fuller fill.
- Twist the knob in the opposite direction to draw the piston up and pull ink into the converter. You'll see the ink rise.
- Lift the pen from the bottle and twist the knob slightly the other way to push any remaining air back out, then draw up again. Repeating this once or twice reduces air bubbles and maximises how much ink you get in.
- Wipe the nib and section clean with a paper towel — there will be ink on the outside. Don't skip this step.
- Screw the barrel back on. Because the nib and feed are already saturated with ink, you can usually start writing straight away.
Step by step: filling with a squeeze converter
Squeeze converters (sometimes called CON-B type, after Pilot's version) use a flexible sac you squeeze directly rather than a knob mechanism.
- Insert the converter into the section.
- Squeeze the body of the converter firmly to expel all the air — do this before dipping.
- Dip the nib fully into the ink.
- Slowly release the converter. The sac will expand back to its original shape, drawing ink in as it does.
- Repeat once or twice to reduce air bubbles and increase the fill.
- Wipe, assemble, and write.
Piston fillers
A piston filler is a pen with the filling mechanism built directly into the barrel. There's no separate converter — the barrel itself becomes the ink reservoir, controlled by a knob at the end. Piston fillers hold considerably more ink than converters, typically at least twice as much, and they're the choice for anyone who writes at length or wants to go longer between fills.
The TWSBI Eco and Diamond range are the most popular piston fillers at beginner and intermediate price points and are stocked by The Journal Shop. At higher price points, Pelikan, Lamy (the 2000), and many Japanese pens also use this system.
Step by step: filling a piston filler
- Uncap the pen. There's no section to remove — the nib is at one end, the piston knob at the other.
- Twist the knob to push the piston all the way forward, expelling air. Again, do this before dipping.
- Submerge the nib fully in the ink bottle.
- Twist the knob in the opposite direction to draw the piston back and pull ink into the barrel. Watch the transparent barrel fill — one of the particular pleasures of a demonstrator pen.
- Expel and refill once to reduce air bubbles and maximise the fill.
- Wipe the nib and section, and you're ready to write.
A note on transparent piston pens: the ink window that lets you see the fill level is one of the reasons TWSBI pens are so satisfying to own. Running low on ink mid-page is never a surprise.
Vacuum fillers
Vacuum fillers work differently to pistons. Where a piston pulls ink in by drawing back a plunger, a vacuum filler uses compressed air and a rapid plunge to create suction — one stroke fills the barrel completely. The mechanism is elegant, the ink capacity is large, and there's a satisfying drama to the fill. TWSBI's Vac700R and Vac Mini use this system.
Step by step: filling a vacuum filler
- Uncap the pen. Locate the blind knob at the end of the barrel.
- Twist the blind knob to unlock the plunger, then pull it back to retract it.
- Push the knob down fully before dipping — this clears air from the pen.
- Submerge the nib fully in the ink.
- Push the blind knob all the way down in a single firm stroke. The vacuum created draws ink into the barrel immediately.
- Screw the blind knob back down most of the way — leave a small gap of around 2mm to avoid activating the safety valve, which seals the ink off entirely. The safety valve is useful on flights and in bags, but you'll want ink flowing for writing.
- Wipe and write.
Eyedroppers
An eyedropper pen has no filling mechanism at all — the entire hollow barrel is the reservoir, filled directly using a dropper or syringe. Ink capacity is enormous: a standard eyedropper pen holds four to eight times more ink than a cartridge. The trade-off is convenience — you need to have a bottle of ink and a dropper or syringe to hand when you want to refill.
Some pens are designed for eyedropper filling from the factory; others can be converted with a silicone grease seal on the section threads. If you're interested in eyedropper conversion, it's worth confirming that your pen is suitable — not all are, and it's worth getting right before filling a barrel with ink.
Step by step: filling an eyedropper pen
- Unscrew the barrel from the section and set the section aside carefully.
- If the pen requires it, apply a thin coat of silicone grease to the section threads to create a watertight seal. This prevents ink leaking from the joint.
- Fill a dropper, syringe, or pipette from your ink bottle.
- Drip or inject ink into the barrel until it's about three-quarters full — don't fill to the absolute top, as expansion from heat can cause leaking.
- Screw the section back on carefully. Cap the pen and leave it nib-down for fifteen minutes before writing.
What ink can I use?
Any ink labelled as fountain pen ink is safe in any fountain pen. Beyond that, here are the things to avoid.
Never use: calligraphy ink, drawing ink, India ink, inkjet printer ink, or any ink not specifically labelled for fountain pens. These contain pigments, shellac, or resins that will clog the feed and potentially ruin the pen permanently. If you've accidentally put the wrong ink in, flush the pen immediately with clean water.
Use with care: shimmering inks (which contain metal particles), pigment-based inks, and iron gall inks are all safe in fountain pens if labelled as such, but require more frequent cleaning — every one to two weeks rather than every month. Don't leave them sitting in a pen for extended periods without use.
The ideal starting point: a straightforward dye-based ink like Diamine, J. Herbin, or Pilot Iroshizuku. These behave impeccably in virtually any pen, clean out easily, and give you a sense of what the pen can do before you explore the more characterful options.
A word on ink bottles
Filling from a nearly-empty bottle can be frustrating — there isn't enough ink in the base to submerge the nib. Most manufacturers design their bottles thoughtfully: Pilot Iroshizuku bottles are wide and low; Diamine bottles have a reservoir built into the lid. When a bottle gets low, tilt it at an angle in a small container to pool the remaining ink in one corner before filling.
Some bottles reward patience more than others. If you find a particular bottle difficult to fill from, a blunt-tipped syringe lets you draw ink directly and transfer it precisely — useful for the last few millilitres of an expensive ink you don't want to waste.
Where to start: browse our fountain pens and fountain-pen-friendly notebooks at The Journal Shop.
