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Fountain Pen Filling Systems

There are lots of ways of getting ink into a fountain pen. Some are very common, while others are rarely, if ever, seen these days. From the invention of the fountain pen, all sorts of different methods were tried, with some amazing innovations over the years. Once the cartridge and converter came along, though, and fountain pens started to be replaced by ballpoints and rollerballs for most people, the innovation died down a lot. There’s still some going on, but not a lot that’s actually new appearing these days.

The Common Types


Diamine Ink Cartridges Pack of 18 by Diamine at Cult PensThe most common way of filling a fountain pen these days, cartridges are super easy and very convenient. When a cartridge is empty, pull it out, and push a new one in. Job done.

For more, see How to Change a Fountain Pen Cartridge, but that’s pretty much it.

The down side is that every cartridge is a bit of single-use plastic, and they don’t hold a lot of ink. But it’s easy to carry spares, and you can refill anywhere.

A lot of different pen brands use standard ‘international’ cartridges, which gives you a lot of choices of ink.

And another advantage is that the vast majority of cartridge-filled pens can also be fitted with a converter, enabling them to use bottled ink. Which brings us nicely to…

Midori MD Fountain Pen Converter by Midori MD at Cult PensConverters

Take out a cartridge, and push a converter in its place, and it converts a cartridge-filled pen into a sort of piston-filler. There are a few cartridges with other mechanisms, but the majority use a piston - wind it down, dip the nib into ink, wind it back up.

See also: Fountain Pen Converters: What They Are and How to Use Them.

With a converter, you have a much wider choice of ink, as there are almost limitless inks available in bottles. And while some can get expensive, there’s plenty of cheap and very good quality ink around too, working out much cheaper than cartridges. And since the glass ink bottles can be recycled, you’re making very little waste.

Refilling does need to be somewhere with a good flat surface, and you might not want to carry a glass bottle around all day just in case you run out of ink, but you could still keep a cartridge or two in a pocket just in case.

Piston Fillers

If converters are effectively piston-fillers, and they’re so good, why would you want an actual piston-only pen? They’ll usually hold a lot more ink than any converter. The whole piston mechanism doesn’t need to fit into the space of a cartridge, so there can be more space for ink. For those who write a lot, it can mean a lot less time spent refilling.

Piston mechanisms are usually very reliable - they’re used in almost all high-end Pelikan fountain pens, some of the most luxurious Montblanc pens, and many of the most popular models from TWSBI and Nahvalur.

Still Around Today

Vacuum Fillers

Vacuum fillers were popular at one time, but they almost disappeared. Like the piston-filler, they can be very reliable, and while they’re perhaps a bit more complex to use, or at least a bit less obvious how to use them, they usually hold even more ink in the same space.

TWSBI VAC Mini Fountain Pen Clear by TWSBI at Cult PensWith a vacuum-filler, there’s a rod that’s pulled up from the back of the pen, then dip the nib in the ink and push the rod back down. A plunger made of some sort of rubber slides down, creating a vacuum behind it - the bottom of the barrel, near the nib, widens on the inside, and air rushes back in. Except it can’t, because you dipped the nib into the ink, so ink has to rush in, and fill the pen up.

It’s harder to explain than it is to do, and definitely takes longer. They fill in seconds, and can fill most of the barrel up with ink.

One added complexity is that many vacuum filled pens include a shut-off valve. With this, when the rod is screwed fully down, the plunger part actually seals off the ink flow just behind the nib. It’s a little bit extra to get used to, but it does serve a useful purpose. When sealed off, there’s very little ink in the feed, so very little ink that can leak or spill if the pen gets knocked or shaken about. But there’s usually still enough for a quick note. Need to write more? Just unscrew the blind cap enough to release the seal - don’t pull it too far, or things could get messy!

It’s a little bit of extra thought, and more than many people want in their pen, but if you’re happy to remember to release that valve as needed, they’re very good pens. They don't have to be very expensive, either, with some great vac-filled pens from TWSBI, and the Nahvalur Original Plus.


An eyedropper is perhaps the simplest filling mechanism around. There really isn’t a mechanism at all. Unscrew the barrel, pour ink into it, and screw it back together. The name comes from the eyedropper you’d usually use to transfer ink into the pen - actually pouring it from a bottle would make a terrible mess of your carpet.

Opus 88 Demonstrator Eye Dropper Fountain Pen Clear by Opus 88 at Cult PensSome eyedroppers look like they’re vacuum fillers - they have the rod down the middle and something similar to the plunger at the end - but they’re actually doing the shut-off valve part of the vac filler, not the rest of it. These are often referred to as ‘Japanese Eyedroppers’, regardless of where they’re from - it’s just a type of pen that was popular in Japan for a while and the name stuck. Most Opus 88 fountain pens are of this type, and they're very popular with fountain pen geeks.

With no filling system to get in the way at all, an eyedropper pen will normally have a higher ink capacity than any other filling system, for the same size of pen. But you not only need a bottle of ink to refill them, but an eyedropper too, and some way of holding the pen barrel upright while you do. That said, unless you write a lot, one fill is probably going to last you a while, and most eyedropper pens have transparent barrels or at least ink windows, so you’ll know if topping up would be a good idea before you leave.

They do have another potential problem, which is the reason for the existence of Japanese Eyedroppers. With all that ink and air right inside the barrel, changes in temperature can push ink out of the pen too quickly. Hold a cool pen in your warm hand, and after a while, ink could start dripping. That shut-off valve can save you if it’s there.

Some of you might be starting to wonder what the difference is between a cartridge pen and an eyedropper, if you just don’t use a cartridge, and fill the barrel up with ink directly. Sometimes there’s a big difference, and sometimes not. It all depends if the barrel is sealed - sometimes there are little air holes, or just a joint between two parts that didn’t need to be sealed.

But some cartridge pens can be used as eyedroppers if you don’t mind a bit of risk. Do a web search first, see if people have tried it. A bit of silicone grease on the threads can help keep things sealed. And proceed cautiously - it’s all very much at your own risk - and that of your carpet!

Some Interesting Historic Fillers

So many different filling systems were tried over the years that it’s impossible to cover them all here. Well, ok, maybe it would be possible, but this article would be huge, and you’d get very bored. Let’s just stick with a few interesting ones.

Lever Fillers

The most common type of fountain pen for many years. A rubber sac inside held the ink, and a lever on the barrel pushed against a thin metal plate, squishing the sac down. When released, it sprang back into shape, drawing in the ink. Simple, worked pretty well. If you happen on an old pen like this, it’s likely the rubber sac will need to be replaced, but there are pen repairers who will do that for a reasonable price.

Conklin 125th Anniversary Mark Twain Crescent Filler Fountain Pen by Conklin at Cult PensConklin made an interesting variation on the lever filler, called the Crescent Filler. The lever was replaced by a crescent, with a locking ring to stop it being squeezed accidentally in your pocket, with the handy side-effect of stopping the pen rolling off your desk. Mark Twain loved them, and they’re still in production today.

Sheaffer Touchdown and Snorkel

Sheaffer was a huge innovator in fountain pens through the 1930s, 40s and 50s. The Touchdown filler was an odd little system that worked well. There was a rubber sac, but it was encased inside a metal tube with holes in it. Between that and the main pen barrel was a sliding metal tube that could be pulled up and down. Little air holes in just the right places meant that when the tube was pulled to the top, it equalised the pressure inside, and did the same when it was at the bottom. But it was sealed up while it moved between. So when it was pushed down from its top position, the air pressure squashed the rubber sac down, but it sprang back into shape when the tube was back in its ‘home’ at the bottom, pulling ink into it through the nib and feed.

Like the vacuum fillers, it’s complicated to explain, but very easy to do. Unscrew the little cap to release the tube, pull it up, dip in to ink, push it down. Pen filled.

The Snorkel is often said to be the most complex filling system ever made. It was based on the Touchdown, but with one addition. The rubber sac inside its metal casing was mounted on the end of a long thin metal tube. This tube usually sat inside the feed, under the nib. But when you undid the little cap on top of the barrel, it first wound the whole inner unit down, so the tube poked out from under the nib. The same Touchdown system then worked to fill the sac through the tube.

A vintage Sheaffer Snorkel pen with its filling tube extended.

And why bother with all that? So you didn’t get ink all over your nib. Yes, all that complexity just to avoid wiping ink off the nib after filling. The amazing thing was that it worked. It worked so well that, apart from usually needing a new rubber sac, most Snorkels still work just fine, 70 years later.

Oh, and they could slurp up the last drops of ink from the bottom of a bottle, so you didn’t waste any ink.

Parker Aerometric

At first glance, the Parker Aerometric looks pretty much like a lever filler, just hidden inside the pen. You take the cap off, then push a little panel to squash down the sac. But the sac was made from a harder-wearing material, to the extent that some still work ok, many years later. And, more importantly, there was a tube running all the way up the inside of the sac. It served two purposes. Firstly, the ink was drawn in through the tube, all the way to the top, falling back into the sac. That meant you could squeeze several times, filling the pen more with each squeeze. That meant it held more ink.

But there was also a tiny hole in the tube, which made the pen able to equalise pressure changes without leaking - the first pen to be specially designed to be much safer to use in flight. As air travel was becoming popular, Parker was there with a pen that could cope with it, all because of a tiny hole hidden away inside.

What to Choose?

But what filling system should you go for? If you don’t know, a cartridge-filled pen that can also use a converter is a pretty safe bet. If you want to use bottled ink, get a converter too if one isn’t included. That way, you can start with cartridges and move to bottled ink if you want to later; or start with bottled ink, but revert to cartridges if you find it’s more hassle than you want.

If you know you want to use bottled ink, a ‘real’ piston-filler will hold more ink, and is still easy to use. Vacuum filled pens and eyedroppers are probably better kept for more experienced fountain pen users, at least partly because it would limit your choices of pen quite a lot.