Fill Me In! A Guide To Fountain Pen Filling Mechanisms (Part Two)

If you're a fountain pen enthusiast, you're probably pretty familiar with cartridges and converters, and maybe even piston-fillers. But did you know that some of the most celebrated pens in the world fill with a vacuum, a crescent-shaped lever, or even an eyedropper?

Last week, in Part One of this series, we learned some surprising details about converters and explored the history and range of piston-fillers. This week, I'll demystify some of the less common, and most fun, filling mechanisms used in modern fountain pens. If you'd like to learn how to get the most complete fill out of a vacuum-filler, or see a remarkable piece of fountain pen history from the Conklin family collection, keep reading!

 

Vacuum Fillers

The first widely successful vacuum-filling fountain pens were released in the 1930s by the W.A. Sheaffer Pen Company, and today, two of the most iconic and desirable modern fountain pens, the Pilot Custom 823 and Visconti Homo Sapiens, use updated versions of the same filling technique.  But, you don't need to buy a gold nib luxury pen to get a taste for vac fillers.  The TWSBI Vac700R, TWSBI Vac Mini, and Nahvalur Original Plus offer entry-level vacuum-filling fountain pens with steel nibs for less than $100.

[Pictured, left to right:  Nahvalur Original Plus, TWSBI Vac700R, Pilot Custom 823 (partially filled with ink), and Visconti Homo Sapiens fountain pens. The Pilot and Visconti both have their end knobs unscrewed, ready for a long writing session!]

Modern vacuum fillers are highly valued for their massive ink capacities and built-in ink shut-off valves that make them ideal for air travel.  Many also feature transparent or translucent bodies that let you watch the fascinating filling process and enjoy the sight of your ink sloshing around inside the barrel while keeping an eye on your ink level.  Most of all, people love vac fillers because the filling process just feels cool. 

Although they can seem a little intimidating at first, and there are a few things about vac fillers that can be frustrating if you don't understand them, they're actually very easy to use once you get the hang of it.

If you look into our Pilot, TWSBI, or Nahvalur display cases, you'll see a few pens with a metal rod down the center of the barrel. Those are the vacuum-fillers. The plunger rod is attached to a flexible gasket that creates the vacuum used to fill the pen and also serves as an internal valve to control ink flow while writing.

[Pictured:  TWSBI Vac700R in Kyanite Blue on the left, and Pilot Custom 823 in Amber on the right, with Pilot Iroshizuku Ku-jaku ink.]

In my photo above, you can see the plunger rod pulled most of the way out on the TWSBI. I left it pushed slightly inward so you can see the black gasket more clearly. The Pilot Custom 823, on the right, has its plunger rod fully pushed in, with the valve closed so that ink in its barrel can't flow to the nib. This protects the pen from leaking while you're transporting it, and is especially useful during air travel, when changes in air pressure can cause the ink inside the barrel to expand and push ink out through the nib.

To use a vacuum-filler:

1) Take off the cap, then unscrew the knob at the end of the barrel (which may look just like the end finial on a cartridge/converter pen) and pull the plunger rod out until it is fully extended. It might be a little harder to pull than you expect, but that's okay! It is meant to pull out, and it will stop when you have reached its full length.

[Pictured:  Pilot Custom 823.]

2) Submerge the pen's nib in ink, and firmly push the plunger back in. You will feel a lot of resistance because you are creating a vacuum. When the plunger reaches the slightly wider section near the top of the barrel, the seal breaks and the vacuum is suddenly released. The pressure equalizes, and ink instantly rushes into the barrel!

3) Leave the nib submerged for a few seconds to allow the pen to finish taking in ink, then wipe off any ink from the grip section with a soft cloth or paper towel. 

Don't worry if the barrel isn't completely full.  This is normal; you'll probably get it about 50%-80% full on a single fill. I'll teach you some tricks in the next section if you want to achieve a fuller fill, but it's also not something most experienced vac filler users stress about. A vacuum filler holds a lot of ink (typically between 1.5 and 2.5 ml, depending on the model), so, even on a partial fill, your ink won't run out for a long time.

4) If you will be storing or carrying the pen, point the nib upwards and screw the knob all the way down, which seals off the ink reservoir from the nib section. Some ink will remain in the pen's feed, so you will still be able to take brief notes.

5) When you are going to be using the pen for a longer writing session, point the nib upwards and unscrew the knob approximately two full rotations (about 2 millimeters) to release the seal and allow ink to flow to the nib.  Leave the valve open until you are finished writing.

[Pictured:  Pilot Custom 823 after filling, with the valve open, ready for writing.  I practiced filling some piston-fillers with inky water to get the hang of it, so I wouldn't waste ink!]

Step five is very important, and many new vacuum-filler owners don't understand it, so our customer service department gets a lot of calls from customers who think their pen has flow issues. But the pen is actually functioning exactly as it's designed to do. All you have to do is crack the knob open to unseal the valve, and the ink will flow perfectly. That's it!

By the way, if your vacuum-filler is designed to allow the cap to be posted while writing, the cap will usually still fit securely even when the back knob is unscrewed. Very cool!

A few notes about maintenance:

If you have a TWSBI vacuum-filler, the pen comes with pictorial instructions showing you how to take it apart and service it, along with a mini wrench, silicone grease, and replacement O-rings hidden in the underside of the tray at the bottom of the box. However, I wouldn't recommend disassembling your pen unless you're completely comfortable doing so. It isn't necessary for routine cleaning and maintenance.

We do sell replacement nib units for TWSBI vacuum-fillers, and it's perfectly fine to unscrew the entire nib unit and replace it with a different one.

Visconti Homo Sapiens owners can also unscrew the entire nib unit (the nib and feed) from the grip section. If you do this, however, use a rubber grip pad rather than your bare fingers to avoid damaging the nib. Do not pull the friction-fit nib and feed out of the collar, and never attempt to remove the plunger rod, back knob, or internal seals yourself. Doing so requires specialized factory tools, and it will void the warranty.

Disassembling a Pilot Custom 823 also voids the warranty, and you should never attempt to do it. Our Pilot representative, Bill, tells me he regularly hears about Custom 823 owners who have damaged their pens trying to take them apart. If the plunger rod on a Custom 823 or Visconti Homo Sapiens becomes stuck or needs lubrication, contact the manufacturer for servicing.

When I opened the valve by turning the end knob and held the pen nib-down, I was able to see the ink draining into the second reservoir.  If I had closed the valve again at this point, I'd have a sealed reservoir with about 0.3 ml to 0.5 ml of ink, similar to the amount that the Kaweco Foldable Mini Converter we talked about in Part One can hold.  This would be the perfect amount to use on an airplane, without worrying about the ink in the larger primary reservoir being affected by changes in air pressure.

[Pictured:  double reservoir Homo Sapiens with ink in both chambers.]

You can also be intentional about locking down your ink in the large reservoir.  Just loosen the valve, hold your pen nib up, and allow the ink to drain behind the plunger, then screw the valve closed again, sealing off the majority of the ink from the nib and feed.  This way, all the ink (except what is saturating the nib and feed) is trapped in the barrel. To resume writing again after using up all the ink from the nib and feed, simply loosen the end cap again and let the ink flow back to the nib!

 

Pump-Vacuum Fillers

Remember Pilot's CON-70 converter from Part One of this series?  All of the core models in the Esterbrook Estie lineup are available with a built-in filling mechanism that works exactly the same way! Just like Pilot's high-capacity converter with its push-button, spring-loaded plunger, these Estie models feature what Esterbrook calls a "push-button piston filling system," which is accessed by unscrewing a blind cap at the end of the barrel.

Pressing the button forces air out of the chamber, and releasing it creates a vacuum that draws in ink. Just like with the CON-70, press and release the button several times to get a complete fill. You will be able to see through the pen's ink window when the ink has reached the top.

Esterbrook describes it as a "specialized, integrated mechanism [that] acts like a vintage pump-filler—invoking the historic heritage of early 20th-century fountain pens to draw massive reservoirs of ink directly inside the barrel."

Esties equipped with the pump-vacuum filling mechanism are easy to recognize by their blind cap, accented with a metal ring. They have a corresponding metal accent ring near the bottom of the cap (also included on other newer Esties), plus two more rings that frame an ink window hidden beneath the cap. It's a classy look, and the ink window and blind cap add a little extra length to both the barrel and the cap. So, if you prefer longer pens and more unusual filling mechanisms, you might enjoy this variation on the classic Estie, which is normally a cartridge/converter pen.

[Pictured:  Esterbrook's "Push-Piston" Estie in Honeycomb, alongside my own classic cartridge/converter Estie in Seaglass.]

 

Crescent Fillers

Like Esterbrook's push-button filling Esties, Conklin's Mark Twain Crescent Filler is an homage to historical fountain pens. Conklin's contemporary pen uses the famous Conklin proprietary filling mechanism designed and patented by the company's founder, Roy Conklin, in 1897. He was later granted official U.S. Patent No. 685,258 for the self-filling fountain pen in October 1901.

At the time, the standard way to fill a fountain pen was by taking it apart and manually dripping ink into the barrel using a glass eyedropper. Conklin wasn't the first inventor to try to improve upon this method, but his simple and effective crescent-filling solution is widely celebrated as the first commercially successful self-filling fountain pen. Its success was in part thanks to famous American author Mark Twain, who loved the pen and became a spokesman for the Conklin company. In a letter of endorsement that was later used in an advertisement, Twain wrote: "I prefer it to ten other fountain pens, because it carries its filler in its own stomach, and I cannot mislay even by art or intention. Also, I prefer it because it is a profanity saver; it cannot roll off the desk."

[Pictured: one of Roy Conklin's own crescent filler pens, and some of his original patents for the self-filling fountain pen, now cared for by the current generation of the Conklin family.]

Roy Conklin was my co-worker Erika's great-great-grandfather (her grandfather's grandfather), and she very kindly brought some of his original patents to Pen Boutique for me to look at and photograph, along with Roy's crescent filler pen, one of her most treasured possessions. Conklin lived in Toledo, Ohio, where he founded the Conklin Pen Company in 1898, but he moved to Virginia later in life, where the family lives now.

Conklin's crescent-filling mechanism works the same way the simple squeeze converters (like Pilot's CON-B) that we talked about in Part One do, but it's a little more sophisticated. If you'll recall, those have a flexible sac that looks like a tiny balloon made of silicone or rubber, enclosed within a rigid housing to which a spring-steel pressure bar is attached. Pressing the bar squeezes the sac to push out air, and releasing it draws in ink.

In Conklin's built-in version, a metal crescent is attached to the pressure bar and protrudes through a slot in the side of the barrel. When the crescent is depressed, it pushes the bar, which squeezes a rubber ink sac inside the pen.

My friend Myk Daigle, who is a vintage pen guru, sent me the cool photo above to show how the pressure bar looks when removed from the pen, with the ink sac below it. This is a vintage pen, but the modern ones are built the same way. In Myk's second photo below, you can see a disassembled modern Mark Twain Crescent Filler side by side with an antique Conklin Model 50.

To prevent the crescent from being pushed accidentally, Conklin's design incorporates a lock ring that rotates around the barrel. When rotated to either side, the ring blocks the space beneath the crescent so it cannot move. You can see the ring in its locked position in the modern pen on the left side of Myk's photo, and also in my photo of Roy Conklin's own pen below.

When you are ready to fill the pen, simply rotate the ring until the gap aligns with the crescent. The crescent is now free to move. You can see what happens inside the pen when you press the crescent in this translucent model, loaned to me by my co-worker Joy.

To fill the pen, depress the crescent to push air out of the internal sac, then immerse the nib in ink and release the crescent. Wait about five seconds for the pen to draw in ink. That's it!

If you want to get an even fuller fill, you can press and release the crescent again, pushing out the remaining air and drawing in more ink. Again, wait for the pen to finish filling, then remove the pen from the ink and wipe the section clean. (If you press the crescent and don't see any more bubbles, you know you have a good fill!) Don't forget to rotate the lock ring back into place to lock the crescent before using your pen.

In honor of Mark Twain's role in popularizing Conklin's crescent filler, the modern version of the pen features Twain's signature on the cap ring. You can see it in my photo below, featuring the new Black & White zebra-pattern Limited Edition model alongside the classic Black Chase version.

 

Eyedropper Fillers

To put it simply, an eyedropper-filled fountain pen, or "eyedropper" for short, is a pen whose entire barrel serves as its ink reservoir. Instead of using a piston, pressure bar, or vacuum-filling mechanism to get ink into the pen, you unscrew the front section and fill the barrel directly using an eyedropper or a blunt syringe to transfer ink from a bottle.

The advantage of this type of pen is that it can hold a lot of ink; however, it's very important that the eyedropper pen be made correctly, have no holes or cracks in the body, and have a watertight seal between the barrel and grip section. Many eyedroppers are pens that the user has modified from a plastic cartridge/converter-style pen (such as a Kaweco Sport or Platinum Preppy) by applying silicone grease to the threads, and, occasionally, adding an O-ring.  If you want to make your own eyedropper, be sure to choose an appropriate pen, and to make sure there are no metal components inside that could corrode.  "Eyedroppering" your pen can be really cool, but it's also risky!  If the pen isn't sealed correctly, you'll have a huge mess on your hands (and on anything else that comes in contact with your leaky pen!).

The earliest fountain pens, introduced in the late 1800s, were primarily eyedropper-fillers, but self-fillers like Conklin's crescent filler were widely adopted by 1915 and had almost completely replaced commercially produced eyedropper-filled pens by the 1920s. Eyedropper-filled pens are pretty uncommon today, although they are still appreciated for their simplicity and the partnership that develops between user and pen. Some of the Victorian-era examples that you can find at pen shows are beautifully ornate and feature wonderfully flexible nibs, but they require a little more patience and intentionality to use than modern pens do.

If you want to experience very user-friendly eyedroppers, modern Japanese-style eyedropper pens like Pilot's magnificent Namiki Emperor or the many fun models made by Taiwanese company Opus 88 are the way to go. They were designed as eyedroppers right from the start and feature an internal ebonite rod attached to a cap at the end of the pen. The rod seals off the feed when the end cap is closed, preventing leaks, then opens to allow a steady flow of ink while writing. This system also keeps the pen from "burping" ink, which can happen with traditional eyedroppers when air trapped inside the barrel expands and forces ink out through the feed. The largest Opus 88 model can hold 3.5 ml of ink, and the huge Namiki Emperor can hold as much as 6 ml!

[Pictured:  Opus 88's Demo model in Yellow resin, alongside Pilot's Namiki Emperor in Black Urushi lacquer.]

Although filling a pen using an eyedropper may sound a little scary, eyedropper-fillers are actually fun to use, and I really enjoyed trying an Opus 88 for an article I updated recently. I've never filled a Namiki Emperor, but the method would be the same.

The process is simple:

1) Disassemble the pen by removing the cap and then unscrewing the grip section from the barrel. It may feel a little harder to turn at first than your cartridge/converter pens, but remember, eyedropper pens need a tight seal so they won't leak.

[Pictured:  disassembled Namiki Emperor, with its eyedropper.]

2) Open the shut-off valve by loosening the end cap at the bottom of the pen. Again, it will be a little hard to turn, but don't be afraid; you won't break it! Keep unscrewing, and use a little elbow grease to pull it out so there's a gap between the threaded part and the barrel of the pen. This step is optional, but it can help prime the pen's feed.

3) Fill the barrel with ink by using the eyedropper provided in your box to suck up ink from a bottle and release it directly into the open barrel of your pen.  You can also use a blunt syringe for this step if you want a little more control.

Remember, eyedropper pens' barrels hold a lot of ink, so you'll need multiple eyedroppers full if you want to fill the pen all the way.

4) Set aside your inky eyedropper or syringe, and, holding the pen with the open end up, screw the grip section back onto the barrel.  Make sure it's fully closed, nice and tight.

5) Now, with the nib facing downward, screw the shut-off valve closed. This will help prime the feed, but you may need to rest the pen with the nib pointing downward for a few minutes to allow the ink to flow into the feed. You can simply stand it in an empty cup with the cap on. In less than five minutes, the pen is ready to write!

6) Similar to a vacuum-filler, a Japanese-style eyedropper needs to have its shut-off valve opened in order for the ink to keep flowing, so unscrew the end cap a little bit and create a small gap if you're going to be using the pen for more than a few quick notes. Unscrewing it so you can see all the threads but not the black rod is a good amount.

When you're done writing, screw the end cap closed again, and this will seal off the feed and stop airflow. You can carry the pen without any worries about it "burping" ink, and the mechanism will keep your pen from leaking if you fly with it and it is exposed to changes in air pressure. With the shut-off valve closed, the ink will run dry after a short time, and no more ink will flow between the barrel and the nib.

A Namiki Emperor, like the one pictured above, is so finely made that the division between the barrel and the end cap is nearly invisible when the shut-off valve is closed.

You can also prime a Japanese-style eyedropper pen's feed when the pen has been sitting for a while to get the ink flowing. All you have to do is unscrew the end cap, pull the piston outward, and push it slowly back in. Unlike with a vacuum-filler, this won't build up pressure and empty the pen. Don't be afraid to pull it out far! This is an especially great trick to have up your sleeve if you're using shimmer ink, which can settle and clog pens. Just use the plunger to expel a drop of ink onto a piece of paper or cloth, and the pen will start writing perfectly again.

I really enjoy how hands-on and straightforward the eyedropper filling process is. It makes me feel in touch with the pen, sort of like the nice feeling of planting something with your hands in the dirt.  Whether using an inexpensive Opus 88 or a Namiki Emperor handmade by the Kokkokai, Pilot's group of dedicated Maki-e artisans, the eyedropper filling experience is a cool callback to historical fountain pens that have evolved over the past 140 or so years into the modern pens we have today. And we can still enjoy using pens, old and new, with all of these filling mechanisms, along with many others that are no longer made.

 

Fill Me In

Do you have a favorite filling mechanism, vintage or modern? I have to admit, I'm partial to piston-filling mechanisms, both in converters and the built-in kind. But they're all fascinating in their own ways, and writing this series has made me want to add more types to my own pen collection.

If you haven't already read Part One, in which I covered converters and piston-fillers, please check it out. Even if you think those topics are pretty basic, there may be information that surprises you! Please let me know in the comments if you have any more tips or insights about filling mechanisms to share, and which filling mechanisms you find most enjoyable or interesting to use. I'd love to hear your thoughts!

-Laura P.

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