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What is an eyedropper pen?

What is an eyedropper pen?

Ross Adams |

What is an eyedropper pen?

An eyedropper fountain pen is a pen with an empty barrel that can be filled entirely with ink without the need for a converter or cartridge, the barrel itself essentially acts as this.

There are a few pens sold primarily on this basis but they are not something you see very often. However there are pens on the market that can be converted from a converter/cartridge use fountain pen into an eyedropper pen. In this blog we will explain how you can do this yourself.

The benefits of an eyedropper pen:

An eyedropper massively increases the amount of ink your pen can hold - up to 6ml! An ink cartridge holds approximately 0.8ml of ink. 

If you are a big writer and enjoy using the same colour ink for long periods an eyedropper means less ink refills.

One of the easiest and cleanest filling methods.

It is a very simple pen as there are very few internal parts. Meaning less maintenance or for things to go wrong.

You don't need to purchase cartridges or converters saving you money.

If you use a demonstrator fountain pen you can see your eyedropper barrel filled with all your favourite ink, even better if it's a shimmer ink!

The cons of an eyedropper:

You need the extra addition of an ink syringe or pipette to fill the barrel.

Can be prone to ink 'burps'. As you use up the ink in the barrel an air bubble forms and the heat from your hand or change in outside temperatures causes a build up of pressure and expands the bubble. In some pens this can force the ink down into the feed and you end up with an expulsion of ink on your paper.

What pen can I convert into an eyedropper?

Most pens can be converted into an eyedropper as long it has an all plastic barrel and thread. Metal pens are not recommended as the ink can corrode the metal damaging your pen or changing the colour of your ink. It sounds obvious but make sure the pen you are using has no breather holes in the barrel - instant leaks!

Recommended pens to convert:


How to convert into an eyedropper and what you need:

  • Silicone grease
  • O-ring
  • Ink syringe or pipette

Start by taking the cartridge/converter out and giving the barrel a clean with some warm soapy water and a cotton bud to dry.

Using your finger put some silicone grease onto the threads of the barrel, this stops the ink travelling up the threads and leaking. Only a small amount is needed, just enough to cover and fill the threads.

For an extra added leak-proof precaution you can add an O-ring to the top of the threads on the grip piece. Stretch it over to the base of the threads (this step is not always entirely necessary).

Fill the barrel with your chosen ink using an ink syringe or pipette. Fill the whole barrel, up to the threads, this will reduce ink 'burps'.

Screw on the grip section. Don't be tempted to tighten it too much. Let the ink flow through to the feed by turning it nib down or if you need to use it straight away gently tap the ink down.



Ink 'Burps' - these can be solved by filling the pen back up from two thirds to full capacity therefore expelling the problematic air bubble.

Is it leaking through the thread?  Make sure the silicone grease is along all of the threads. You can do this by screwing the barrel onto the thread back and forth a few times. The addition of an O-ring could help any leaks if you don't already have one on the pen.

Store the pen nib facing up to avoid any large ink leaks.

It is not advised to clip your eyedropper in your shirt pocket - just in case!

To avoid any leaks whilst taking your pen on a flight, fill it up with ink. The air pressure causes the air bubble to expand and push the ink up through the nib and feed.

All this being said, not all eyedroppers leak and most people have great experiences with them. It is definitely something to try out if you have been wondering about an eyedropper pen.