Pens and Pencils | Reviews and Data

Best Fountain Pens for Eyedropper Conversion (And How To Do It)

Converting a fountain pen to an eyedropper is a quick and fun job… so long as you choose the right pen! It’s quick to do, quite cheap, and you can often double, or even triple, your pen’s ink capacity.

What Is An Eyedropper Pen?

An eyedropper is a fountain pen that does not have a filling mechanism of its own, rather it uses an eyedropper (or pipette, etc.) to fill it. The body of the pen is made of plastic and the ink sits directly inside the body. This body is an empty cavity, similar to a piston-filling pen, but there is no piston.

And eyedropper is the simplest and highest capacity type of fountain pen.

Platinum Preppy and Pilot Petit1

Identifying Eyedropper Candidates

If you want to convert a fountain pen to be an eyedropper you are looking for a few very basic (and very obvious) features. First of all, you need a pen with a non-reactive body for the ink to touch. This is the case because the ink will no longer be in a cartridge, sac, or converter. This usually means a fully plastic body with plastic threads, but it could mean glass. What you mainly want to avoid are metal pen bodies or plastic ones with exposed metal threads.

The problem with metal isn’t so much that the pen will leak, but rather that some inks can corrode metal. This could ruin the pen, affect the color of the ink, affect the longevity of the ink on paper, or cause pen leaks over time.

Second, you want a pen body with no holes in it. If the body is acting a your cartridge then any hole would be major problems, right? The problem here is that holes make manufacturing easier, so they appear very often. So countries make holes mandatory for safety reasons as well, just in case a pen cap is ever swallowed. Just look at something like the Lamy Vista, which would be an ideal candidate but has two holes running along the side of the body.

Lastly, and this is totally up to you, but you probably want a pen that isn’t too expensive. This is normally not an issue because of the requirement for plastic parts, but it’s something to keep in mind anyway.

Things You Need For a Conversion

You don’t need much in the way of additional stuff to convert a pen to an eyedropper. Basically you just want a few things to ensure the seal between the pen body and section is very secure and to prevent leaks. Most people recommend using both of these:

The o-ring goes at the bottom of the threading and acts as stopped. This way when you screw the body down, there is some pressure against it from the grip section and it’s less likely to loosen over time. The silicone grease goes on the threads and prevents any ink from snaking its way down the threads over time.

The Best Eyedropper Fountain Pens

These are pens with plastic bodies with no holes in them, plastic threads on the body, and can be locked down securely. There is always some risk of ink leakage when doing an eyedropper conversion, but these pens should withstand the test of time. Just make sure to use the silicone grease and o-ring and to not overtighten the body when screwing it down!

Platinum Preppy Eyedropper Deep Dive


In order to test out fountain pen inks I’ve converted dozens of Platinum Preppy and Preppy Crystal pens to eyedroppers. For some time my preferred way of testing an ink thoroughly was simply to fill a Preppy with a 2 ml sample and then use the pen. This method is simple and effective from a methodological standpoint, though not very cheap.

I started really doing this at scale in the Spring of 2018 in order to test a large set of inks. The initial batch was about 15 pens and then over the next few months I did about 15 more.

I just — in December of 2019 — cleaned out the first set of pens in order to see if they could be cleaned and used as eyedroppers of another color. Before this time I had refilled a few of the pens with no problems. Out of the 15 pens I started with:

  • 10 survived and were cleaned
  • 3 cracked or leaked and were thrown out
  • 2 status unknown (lost or given away)

So basically out of the 13 pens I have access to, 10 survived. Not a bad hit rate for a year-old, $3 pen!

So yes, the Platinum Preppy, as well as the Preppy Crystal and Prefounte, is a great choice for an eyedropper conversion.