At the beginning of fountain pens, there was nothing in the line of a “filler” if you take that word to mean a specifically-designed mechanism for getting ink into a pen. Pens were, in essence, very thin ink bottles with a cleverly-made dispenser built into the lid. When refill time came around, one just unscrewed one end and dumped more ink inside.
Of course, this is pretty tricky with something pen-sized, as the combination of liquid surface tension and the limits of human motor control render pouring fluid into anything smaller than a cordial glass messy. Thus, the application of the eyedropper to the question, and the application of the tool’s name to the pen itself. I actually use a 1 ml insulin syringe, available thanks to an ill cat in the extended family, but I recommend a 5 or 10 ml syringe intended for giving medication to children– they’re not expensive.
The main charm of the eyedropper pen is its simplicity. There’s nothing in there but space to store ink, so if you’ve got some serious writing to do, an eyedropper is the way to go. Most self-filling pens don’t carry more than 1.5 ml of ink, but even the rather slender Waterman 12 has room inside for near to 3 ml.
The actual filling is a very fraught experience– one needs to balance the barrel, a long, thin tube, most frequently with a more or less rounded bottom, while manipulating whatever thing it is one is using to transfer ink from the bottle, and continue to balance it while one recovers the section from wherever it has rolled off to and endeavours to get it screwed back on. I’ve yet to have a disasterous spill yet, but I can easily imagine one.
The main drawback to the eyedropper is that it tends to dribble. This is a result of a combination of old feed styles and thermal expansion. Eyedroppers are fairly popular in India, it seems, and I guess in a part of the world where air and body temperature is frequently about the same, this is less of an issue.
The feed simplicity is also sort of culpable in the dribbling. With early pens, there wasn’t much choice, but with modern eyedroppers, makers know what a feed is capable of and a dripping eyedropper is something one might raise an eyebrow at, considering that piston- and vacuum-filling pens also store ink in the barrel. I certainly raise my eyebrows, although there are some sublimely expensive ones with interesting anti-dribble controls that I dare not look askance at for fear someone will expect me to pay for the privilege.
The other big issue in eyedroppers is the joint between barrel and section. Unlike most pens, where the reservoir is more or less permanently sealed, in eyedroppers this remains a point of potential escape for the ink. Some more advanced models rely on o-rings, but most require regular applications of some kind of hydrophobic material, like bees-wax (better, if you can find a softer sort) or pure silicone grease (works, but it’s meant to lubricate and that can lead to unexpected pen-opening), which keeps the ink in its place without damaging the material the pen is made from. Failure to renew this protective every few fillings leads to seepage, right where your fingers meet the pen. Do not use petroleum jelly, as it attacks many of the materials from which pens are made. There are some who maintain that the tolerances of the old rubber pens were such that a silicon grease is really overdoing it, but I’m a belt’n’suspenders chap in this regard. Applications of grease and o-rings can also render some cartridge pens into eyedroppers, provided there are no metal fittings that don’t regularly contact ink (these would corrode) and no holes in the barrel walls.
Loading an Eyedropper Pen Step by Step (applies to Safety Pens as well, leaving out steps 4B, 8, 9 and 10):
- Get a paper towel or other pen-wiper and eyedropper or syringe.
- Remove cap from ink bottle.
- Hold pen point upward.
- cap from pen and
- section from barrel; the joint may be in a surprising place, as some “center joint” or “jointless” pens sought to keep a possibly leaky seam away from fingers.
- Insert dropper/syringe in ink and draw some out.
- Dribble ink into barrel of the pen– unless the pen is transparent, go slowly to avoid a surprise over-filling, and remember to leave some space for the section to go back in.
- Set dropper on wiper to avoid stains.
- Replace section on barrel. When it is about 5/6ths screwed down, stop.
- Turn pen point-down over ink bottle. Finish screwing in the section. This will load the feed.
- Wipe point to clear any hanging drops from step 9, and the joint to clean up any ink that might have escaped previously.
- Replace caps.
- Clean the dropper out with water. Also, you may need to wash your hands.