Fountain pens are one of the most fascinating writing instruments ever invented. The fountain pen revolutionized writing as it allowed people to write continuously without having to dip their pens every few words. Today, most fountain pens are fed ink either through cartridges, converters, or an internal filling system. However, many fountain pen enthusiasts like to convert a standard fountain pen into an eyedropper pen.
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In eyedropper pens, the ink is filled directly into the barrel instead of using one of the above filling systems. This is particularly sought-after by marathon writers or serious pen enthusiasts, as eyedropper pens hold far more ink than any other filling system. Learn how to do a fountain pen eyedropper conversion with our step-by-step guide.
Materials Needed for the Conversion Process
Before starting, gather all your necessary materials. To complete the conversion process, you’ll need:
For this guide, I’ll be using the Platinum Preppy to demonstrate. While all other materials will most likely already be in your fountain pen arsenal (including silicone grease that comes with many internal-filling pens such as the TWSBI Eco), you will most likely not have an o-ring. An o-ring is not strictly necessary and is not always used by other fountain pen experts, but I think it adds a layer of protection that is worth the few dollars.
Most fountain pens work perfectly with a 9mm OD (outer diameter) and 7mm ID (inner diameter) o-ring.
How To Do A Fountain Pen Eyedropper Conversion
Now let’s get into the nitty-gritty of a fountain pen eyedropper conversion. Follow the steps below.
1. Disassemble the Pen and Clean
Unscrew the barrel from the grip and remove any cartridge or converter if there is one. If you haven’t already, clean all parts to ensure no ink residue is left. Then dry the pen completely before moving on.

2. Seal the Pen
Find the threads at the base of the grip and stretch the o-ring onto the base of the threads. Then apply a small amount of silicone grease to coat the threads with your finger or a cotton swab. Only apply enough to cover the threads lightly; any excess will ooze out when you reassemble the pen.

3. Fill the Dropper or Syringe with Ink
Take your ink of choice and fill either a pipette or syringe. Then insert the pipette or syringe into the barrel and dispense the ink.

4. Fill Barrel with Ink
To prevent spills, insert the pipette or syringe as far into the barrel as possible. Then slowly raise it as the ink level rises. If at all possible, avoid squeezing air bubbles into the ink, as this will cause it to spurt out.

5. Reassemble Pen
Keeping the barrel steady, reinsert the nib section of the pen and screw it in. Then, recap it and set it nib down in a cup or other container for a few minutes to allow the ink the properly saturate the feed. To help get the ink flowing, you can scribble a few times on scrap paper.

Tips for Eyedropper Pens
- Keep plenty of ink in your pen to prevent dripping.
Eyedropper pens are particularly sensitive to temperature changes. The warmth in your hand can change the temperature inside the barrel, causing the air to expand and forcing too much ink into the feed. Keeping your pen at least ⅓ full can prevent this from happening.
- Only use fountain pen ink in your eyedropper pens.
When attempting an eyedropper conversion, filling your pen with any ink might be tempting, but it’s important to only use fountain pen ink. Calligraphy ink, drawing ink, or india ink all contain binders and particles that will clog the mechanisms in a fountain pen. See our list of favorite fountain pen inks.
- Be careful with syringes.
For anything involving fountain pens, only use syringes that have blunt needles and have been cleaned. Sharp needles, such as those used for medical purposes, are never necessary for fountain pen filling and can be dangerous.

What Pens to Use for an Eyedropper Conversion
Personally, I used the Platinum Preppy as the example for this tutorial, but you can use almost any fountain pen. However, I recommend the pens have:
- Watertight Barrel
- No Metal Parts that Touch the Ink
- No Threaded Caps
The watertight barrel ensures that, obviously, no ink will leak out of any holes. Some inks can corrode metal, so they will quickly ruin any metal parts that come in contact with the ink. And finally, while it’s possible to use a cap that screws onto the pen (like a Kaweco Sport), it’s really easy to accidentally unscrew the barrel while trying to unscrew the cap, which will cause a huge mess as nothing is holding the ink in if the barrel and grip section were to unscrew.
Here are some pens that are eyedropper-compatible.
Modifying Pens

For any pens that have small holes in them, you can use a two-part epoxy to fill in the holes. Prepare the epoxy according to the instructions on the box and then apply it to the holes using a disposable tool like a popsicle stick.

Let the epoxy cure for the required time in a safe place where the epoxy won’t touch any surfaces or other objects.
When the epoxy has hardened, test the barrel by filling it with water. If no water leaks, let the barrel dry completely and then complete the eyedropper process as described above. If the water does leak, reapply the epoxy and test again.
Here are some modifiable pens I would recommend:
Advantages of Using an Eyedropper Pen
- Larger Ink Capacity
The average pen cartridge holds less than a milliliter of ink, while an eyedropper pen can hold up to five milliliters of ink, depending on the size of the barrel.
- Easy to Clean
Because there are fewer parts and mechanisms in an eyedropper pen, there are fewer things to clean.
- Simple Assembly
Again, there are fewer parts, therefore, there are fewer steps to assembling the pen.
That being said, eyedropper pens are not without issues. There might be growing pains for first-timers while getting used to filling and maintaining the pen. It can also be frustrating if you choose the wrong fountain pen to convert. However, with a little time and patience, you can easily transition from using cartridges to an eyedropper conversion.
Converting a fountain pen into an eyedropper is a simple and cost-effective way to increase the ink capacity of your favorite writing instrument. With just a few basic tools and some silicone grease, you can transform your pen into a reliable and efficient writing tool that will last for years. By following the steps outlined above, you can enjoy the benefits of an eyedropper conversion while also saving money on expensive cartridges or refills.
Hopefully you’ve learned how to do a fountain pen eyedropper conversion or been inspired to do so. If you have any questions about the process or want to share your own experiences, leave a comment below or send us a message.
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