Fountain Pen Guide Series, Session 2: The Difference A Filling System Makes

March 24, 2021-Kirk Hale

Hello everyone, I am back again with the long-overdue, second session in our fountain pen guide. This time we will talk about filling systems. The usual stuff applies here: any word that is difficult to understand will have a definition placed in the glossary at the bottom of the page. If there’s any other word I don’t address that is still confusing, post a comment or chuck me an email using my contact form and I’ll get back to you!

Session 2: The Difference A Filling System Makes

Filling systems may seem like just a medium for storing ink in your pen, and for the most part that is correct, but your choice of filling system essentially dictates longevity of a single fill, flow, pen size, versatility, and many other factors that may not be obvious at first. Price is also another factor, with many pens coming in a variety of different filling systems at a significant price difference.

Some of you are also unaware that fountain pens even come with systems apart from the regular cartridge fillers. Let me first go through some of the more popular filling systems and how they work just to give you some perspective on the vast variety available. Also check out the ratings for each system for convenience, cleaning, wastage, and longevity rated out of 5.

Convenience: The ease of use of the filler and different features that make filling faster

Cleaning: How easy it is to empty the pen completely in order to switch ink colours/store the pen

Wastage: The amount of parts and materials that get wasted between fills or during maintenance

Longevity: How long a fill lasts before you need to refill (aka ink capacity)

Total: A total of all the points; should not be taken as a “ranking”

The Types of Filling Systems

– Cartridge/Converter

Often abbreviated to C/C, the cartridge converter was pioneered by the Platinum pen company in Japan not too long ago. It’s now the most common filling system in modern pens, and for good reason. It allows cartridges* of ink to be carried around and swapped in and out while you’re on the go, which is incredibly convenient. Before cartridges, you would need to carry around a bottle of ink, or buy some sort of expensive travel inkpot* to cut down on the bulk, but they are still nowhere near as convenient. A converter* can also be purchased in order to fill from an ink bottle, so you don’t lose the colour versatility of other systems. In fact, a huge array of colours available in bottle form are also available in cartridge form, so you may not even need a converter to write with your favourite ink.

Another positive about the cartridge system is it is easy to clean. Either throw out the cartridge or simply wash out the converter, and then run some water through the nib unit*. It can take a while to completely clean out every drop, however. In my opinion, the best advantage to the C/C system is it is very cheap. Pens don’t need to have expensive and intricate systems made from many small parts in order to write, because a cheap plastic cartridge takes care of that.

When choosing a pen with a C/C system, you should see what cartridge options are available. Some brands’ converters can be unreliable so you should read up on that, and a lot of companies use proprietary cartridges (such as Pilot, Lamy, Platinum, Sailor, and many others), but others make use of the Standard International cartridge system, which is the most widely available cartridge design in the world. J Herbin, for example, makes their inks in Standard International cartridge versions. Some companies such as Platinum also sell adapters for Standard International cartridges, so you can use them in their pens too.

The only downside is capacity, with cartridges being much less capacious than other fillers, and converters having even less space inside them (because a lot of it is taken up by the plunger mechanism).

Convenience: 5/5

Cleaning: 4/5

Wastage: 2/5

Longevity: 2/5

Total: 13/20

– Piston

The piston filler is the favourite for those that want a high capacity, easy-to-fill system. Cleaning is also pretty easy! Piston fillers typically have a twisting knob on the end that screws down a plunger inside the body of the pen. Twisting the knob the other way sucks up ink into the pen. It’s a fairly simply system much like a syringe, but trying to dismantle and maintain these systems can be very difficult, which can sometimes be necessary to clean or lubricate them. This only needs to be done once a year or two, however.

Piston fillers are hugely capacious, using the pen’s body as an ink tank*. This isn’t true for all cases, with Sailor’s Realo pens being a prime example: they only have a 1mL capacity or thereabouts, which is not exactly huge.

A price premium also comes with piston fillers vs their cartridge counterparts. The Sailor Realo, again, carries a $100+ premium over the C/C versions, which is not really worth it in my opinion. One of the best and cheapest piston filling pens is the TWSBI 540, which is an exceptional pen sitting around the $70 mark and one of my favourites. The TWSBI Mini is also a fantastic option for those who want a smaller version of the 540.

Cleaning is easy. Just fill the pen with clean water a few times and most of the ink should be out.

The downside is that it is not as convenient as cartridges, being exclusively filled from the bottle. The huge capacity means that you won’t need to fill as often, however.

Convenience: 4/5

Cleaning: 4/5

Wastage: 5/5

Longevity: 4/5

Total: 17/20

– Eyedropper

Eyedroppers are the highest capacity fillers available. Eyedroppers get their name from the way you fill them, using an eyedropper* to transfer ink from the bottle to the pen. These fillers use the entire pen body as an ink reservoir, which yield massive capacities. The huge downside to these pens is both the lack of an internal filling mechanism and the tendency to leak. I would rarely take an eyedropper pen outside of the house, because they rely on the pen being 100% airtight in order to be functional. This is achieved by cutting down on the number of different parts, making parts have huge screwing sections to increase the travel distance for ink to escape the pen, and by using silicone grease* to “seal” parts of the pen that have gaps.

It seems a quick-and-dirty solution to filling a pen, and it is. Many, many cartridge filling pens can be made into eyedroppers by sealing any possible leaks and filling the body without the cartridge in place (like the bottom two Platinum Preppy’s in the photo). This is great for cheaper pens, but expensive pens shouldn’t be converted as a lot of inks can stain the inner walls of the pen body. Because of this, you rarely find premium pens with eyedropper fillers.

Cleaning, however, is fairly easy as you can just wash out the pen body.

Convenience: 1/5

Cleaning: 3/5

Wastage: 5/5

Longevity: 5/5

Total: 14/20

– Sac Fillers

Sac fillers are amongst the most common filling types EVER. Most fountain pens ever made used a sac in one way or another. In fact, the most popular fountain pen in history, the Parker 51, used either an aerometric* or vacumatic filler*, with some also using button fillers, all making use of a sac. Sacs are typically made from a substance that’s like rubber, which is pliable, but strong. This allows them to be twisted, squeezed, and pressed all whilst keeping a good seal. Old pens commonly have a lever on the side that squeezes the sac in the pen in order to fill. Modern usage of sacs in pens are in the form of press-bar fillers, which are like a squeezy converter that you can put in your pen. The Pilot CON-20 is a good example of this. Some pens also have a bulb filling mechanism*, like those made by Edison, which also uses a sac. Sac fillers must be filled from a bottle and typically don’t last very long due to their low ink capacity.

There are many downsides to sac fillers though. Sacs are guaranteed to perish after a certain amount of time, with many old pens having dried up, hard sacs inside that are both difficult to remove and replace. Sacs also need to be sealed on many pens via shellac*, which makes it rather difficult to put the sac on and also makes it a little difficult to get a 100% seal. They also need to be cut to size (after you buy the correct diameter sac) and many filling mechanisms require a lot of know-how before they can be properly repaired. Poorly placed sacs lead to leaks when filled. Another downside is cleaning; sacs almost always have a little bit of air left inside after filling and ink tends to cling to the walls of the sac, so you have to repeatedly flush out the pen to get every last bit of ink out. I personally like to slip a small brush inside and carefully scrub the walls of the sac to get ink remnants out. Repairing even the most basic of sac fillers involves several different tools and materials, and a bit of knowledge. I myself have broken several pens because I wasn’t 100% aware of how the pen was constructed.

Convenience: 3/5

Cleaning: 1/5

Wastage: 4/5

Longevity: 2/5

Total: 10/20

– Sheaffer Snorkel and Touchdown Fillers

The Touchdown mechanism is an exclusive Sheaffer invention present on many old Sheaffer pens from the early to mid 1900s onwards. Despite being a sac filler, it deserves its own section because of how absolutely unique the filling system is. The system has since been phased out in favour of cartridge-based fillers, but many pens are still available today on eBay and similar marketplaces for surprisingly low prices. The Snorkel is a very similar mechanism, but is quite different in a lot of ways as well.

The way a Touchdown filler works is by pulling a rod out the back of the pen, then pushing it back in. This action creates pressure in the pen which squeezes the sac inside. Once the tube has been pushed in far enough, this pressure is released and the sac expands, sucking up ink through the nib end of the pen. A Snorkel filler is far more complicated but even easier to use. Unscrewing the knob on the end extends a “Snorkel tube” out from underneath the nib, and releases the rod that is then pulled out and then pushed back in the same way as a Touchdown filler, except the ink is sucked up through the Snorkel tube instead. This means that you don’t need to put the nib in the ink and don’t need to wipe ink off the nib afterwards! A huge convenience!

The major downside is maintenance. I have repaired a few Snorkel fillers and there is a gargantuan amount of work and parts that go into replacing a hard sac. I mean, in order to fix a completely non-operational Snorkel involves a proprietary rubber gasket, a small rubber O-ring of an exact size, a small sac cut to the EXACT size needed, a screwdriver, heat source, tweezers, rubber pliers, shellac, talcum powder*, about 2-3 hours of fixing time, as well as around 24 hours of drying time for the shellac, AND a lot of know-how and patience to get every little tiny piece placed just right. Replacing the sac on a Touchdown filler is far, far easier and is no more difficult than replacing a sac on a lever-filler, however.

They are also notoriously difficult to clean. For some reason it takes 3-4 pumps of the Touchdown tube to get all of the liquid out of the pen, so there’s always at least a little bit of ink left inside. It has taken me up to 10 minutes of continuous pumping to clean some of these pens, which is fairly ridiculous if you just want to change ink colours quickly. The sac size needed is also very small, so ink capacity is quite low.

Convenience: 5/5

Cleaning: 1/5

Wastage: 3/5

Longevity: 2/5

Total: 10/20

– Dip Pens

Dip pens have been around ever since the first stroke of ink was placed onto paper. As the name would suggest, dip pens involve dipping the pen tip into an ink bottle and writing until it goes dry, then dipping it again, much like a paintbrush. Dip pens typically have a body made from wood or a similar strong material, and a large metal nib*. Long ago, quill pens were made from feathers, with a tip cut into the correct shape. These pens didn’t last very long, and typically required a fresh tip to be cut every so often.

(I don’t own any dip pens, so I don’t have a photo!!)

These days you would only really use a dip pen for artistic writing, because you tend to get a lot of flex* from dip nibs, but I have heard of them being used as general writing pens as well. Dip pens are great because you can buy a body and then put one of a huge array of vintage and modern nibs onto it, making it extremely versatile. There are even dip pens made from glass, which are still available today (J. Herbin makes a great range of glass pens). The obvious downside is the constant need to have an ink bottle next to you and dipping the nib every line or so, but this also means you can instantly change ink colours as well. They’re quite easy to clean, and the small amount of parts and wide availability of very cheap nibs make dip pens very unique and easily maintained.

Convenience: 2/5

Cleaning: 5/5

Wastage: 5/5

Longevity: 1/5

Total: 13/20

– Vacuum Fillers

Vacuum (or “Vac”) fillers are similar to piston fillers in terms of looks, but they’re actually completely different to any of the others on this list. Vac fillers were commonly available a while ago in a lot of Sheaffer pens, and are still available today in pens like the TWSBI VAC700, Pilot Custom 823, Visconti pens, and some Omas pen models too (although Visconti’s system is apparently slightly different to traditional vacuum systems).

Vacuum fillers have a knob on the back that is unscrewed (a la piston fillers), which when pulled extends out of the pen, pulling an inner rod with it. On the other end of this rod is typically a rubber gasket, amongst other things (depending on the pen). The body is hollow, and that is where the ink stored, but the space gets wider closer to the nib end of the pen. When you pull the rod out, the rubber gasket goes from sitting freely in the wide space down the bottom, to being held in the narrower area above, which creates a seal around the gasket. This creates a fair amount of pressure as you pull. When you push the rod back in and the gasket part gets down to the wider end of the reservoir, air is sucked in through the nib, past the gasket, occupying the space behind the gasket (or when filling, ink is sucked in). It’s a great system that gives it a higher capacity than most piston fillers, but it’s held back by being difficult to fill all the way. You have to use certain techniques and/or special ink bottles to completely fill a vac pen, but the amount of ink that they carry even when partially filled is usually more than double your typical cartridge.

Another feature that’s both useful and annoying is that when you screw the knob back in, the rubber gasket seals over the end of the feed, sealing off the nib end from the ink reservoir. This is fantastic to prevent leaks, especially when flying*, but is annoying because you have to half-unscrew the knob whenever your want to write. Typically a pen can write a few pages with just the ink in the feed, but forgetting to unscrew it, having it dry out, then waiting for the ink to come back to the nib can be quite irritating. Because these pens don’t fill all the way in one go, cleaning is relatively difficult as well. Maintenance is also nigh impossible because of the proprietary construction of the rod, gasket, and seal at the back of the pen. I would recommend getting your vac filler professionally repaired if you run into any troubles.

A crudely drawn diagram of how vac fillers work

Convenience: 3/5

Cleaning: 2/5

Wastage: 5/5

Longevity: 4/5

Total: 14/20

– Other filling systems of note (reference purposes only)

Others include the Omas cartridge fillers, which have a section that you pull out the back of the pen and load with a cartridge, then push back in to fill the pen.

Twist fillers like the Swan Leverless are sac fillers that have a knob on the end that twists the sac inside to fill it.

Visconti have made a new “mosquito filler” that is like a vac filler with a removable tube that you slip on the nib end of the pen to give a Sheaffer Snorkel “no wiping” convenience.

The Fountainbel Bulk Filler is a very cool proprietary syringe filler where you can unscrew the gasket from the rod within the pen to allow the “plunger” to be depressed and stored within the pen. Thank you Francis Goossens for clarification on this point! Please read his comments below for a great explanation of this filler.

Crescent fillers have a sac inside that is squeezed when you press down on a disc that protrudes from the pen body.

Capillary fillers are for patient folk; the pen just sits in an ink bottle and fills by slowly soaking ink up into the feed like a sponge.

Wrap Up

So there you have it! I hope this helps you understand why pens are made with different filling systems and that each one has its positives and negatives. There isn’t a perfect filling system out there, but I think the winner in my mind is the…

Piston filler!

Piston fillers are my favourites because a lot of my favourite pens are piston fillers, but also because they’re easy to clean, hold a ton of ink, rarely leak, and rarely need servicing. They’re also one of the cheaper non-cartridge filling systems on the market and are quite common too!

What’s your favourite? Let me know in the comments, and feel free to tell me about any unique filling systems you’ve seen in the past that I’ve missed out on.

 <- Previous Session: Nibs and Feeds


Cartridge: Typically made from plastic, cartridges are very cheap “canisters” of ink that have a hole on one end to insert into a pen. 

Travel inkpot: A small, specially designed vial of ink that you can slip into a pocket or briefcase that allows you to fill your pen without bringing around a large bottle of ink.

Converter: A cartridge shaped insert that has a plunger inside to draw ink into the pen from a bottle.

Nib unit: The front part of the pen that holds the nib (writing tip) and the feed inside.

Ink tank: Another name for reservoir, essentially an area designed to carry ink.

Eyedropper: A tube with a squeezable part on the end to suck up ink into the tube.

Silicone grease: A safe lubricant for use in pens. It won’t damage pen parts and can also be used as a seal for making pen parts airtight. Any part in a pen that slides against another part should usually be lubricated with silicone grease.

Aerometric filler: A Parker-designed filling mechanism that is like a press bar filler, except it has a tube in the filler that ink flows through which leads to a better fill. Aerometric fillers also used a different type of sac made from “Pli-Glass” which is more resistant to ink corrosion. Old aerometric pens bought today will rarely need a sac replacement for this reason.

Vacumatic filler: Present on many premium Parker pens from the mid 1900s, the Vacumatic filler used a diaphragm made from sac material, and a button on the rear of the pen that “pumped” this diaphragm back and forth to draw ink into the pen body.

Bulb filler: These fillers work much like an eyedropper, with a sac on the rear of the pen that you squeeze repeatedly to pull ink into the large reservoir.

Shellac: A brown, glue like substance that is used to stick pen pieces together, typically sacs onto the nib section. It is quite difficult to use, as it dries fairly quickly. Shellac is used because it doesn’t damage pen parts, and softens when lightly heated. This is why a heat source is needed to replace sacs on old pens.

Talcum powder: A white powder applied to freshly replaced pen sacs. This is required when replacing sacs because it creates a layer between any pen parts and the sac that minimises friction, so the sac will last longer. Baby powder is NOT a suitable substitute because it contains chemicals that can damage the sac; only 100% talc or french chalk will do.

Dip pen nibs: Typically larger than normal nibs, dip pen nibs have a small protrusion at the base that allows them to be attached to dip pen handles. Normal nibs are not interchangeable with dip nibs and vice versa because they are a totally different design. Dip nibs are normally cheap, bought in packs, and are still made today.

Flex: Spreading of the nib that allows you to control how wide the nib writes by varying the pressure applied to it.

Flying with pens: Because of the pressure changes at altitude, being in a plane with a fountain pen can sometimes lead to ink being drawn out of the nib and into the cap (and sometimes your pocket). To prevent this, buy a pen that seals the feed off, or completely fill the pen so there are no air gaps for pressure to build in. You could also empty the pen, but that’s no fun is it?

Kirk Hale

Kirk developed a passion for writing since the age of 8, since then, he has been collecting pens and then extended the hobby to collect stationery and art supplies. An extension of that hobby resulted in this blog about pens, pencils and everything in between.
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