Kaweco Eyedropper Leak Troubleshooting

I have had a couple of people email me about troubleshooting their Kaweco eyedropper conversions. They have been getting some leaking, not from the threads on the body of the pen where you might think, but from the nib. There are three things to check in this situation:

  1. Ink Level- any eyedropper pen has the potential to leak or ‘burp’ ink when it’s less than half full. The more air in the pen body, the more likely your hands will heat up the air inside and increase the pressure and there’s only one place for that pressure to release….through the nib. If this leaking happens while you write, try filling your pen back up, that should help.
  2. Nib Setting- The nibs on the Kaweco pens are friction-fit, so they can be pulled out with relative ease. Make sure the nib and feed are set all the way into the pen, if not then it will leak.
  3. Ink Disagreement- Some inks are just better suited than others for eyedropper conversions in a given pen. The viscosity and flow is different for some inks than others, and any differences are amplified by the eyedropper conversion. Some inks will be slightly drier, and some will want to gush and burp. Since eyedropper conversions are sort of an ‘after-market’ conversion, some experimenting will be required.
Hopefully this pointers will help you to troubleshoot your Kaweco eyedropper conversion. Post in the comments or shoot me an email if you have any questions.
2017-10-11T03:12:01+00:00 October 28th, 2011|Tips & Tricks|17 Comments
  • Hey Brian, thanks for the video. Informative as always. I have two Kawecos that I've converted to use an eyedropper fill, one fountain and one rollerball. I also have a Noodler's refillable rollerball. The two rollerballs have a much greater tendency to leak from the nib, the Noodler's more so than the Kaweco, even though it seems to have a smaller ink reservoir. In the video you mention that some inks may be better suited to eyedropper fills—Would you mind giving a couple of examples? I'm trying to get my head around this idea some inks are drier than others. Thanks so much!

  • I was always under the impression that air pressure inside
    plains decreased as you go up in elevation. The decrease in pressure causes an increase
    in the volume of air inside the pen pushing the ink out.

    Boyle’s Law ( pressure1 * volume1 = pressure2 * volume2 )


    If pressure does increase I could see that being a problem to.
    If the air volume gets too small more air will come in through the feed. While you
    land the pressure goes down again but this time because there are more air molecules
    (from the extra air that came in at high pressure) the volume will expand to a
    volume bigger than the original. 


    • The pressure inside the pen is still at atmospheric. When you increase in elevation, the pressure outside is now lower than inside the pen. To equalize the pressure (high pressure to low pressure), the air inside the pen is forced out, along with any ink.

      Hope that helps!

  • Christina Pham

    Good tips Brian! I was doing field work with my research team earlier this year and we drove up to perhaps 6000' elevation. When I checked on the pens that were in my case after the trip, just about all my fountain pens had 'burped'. It would have been good to know this before, or maybe I just didn't think about it because I'm not a flyer. =)

  • Very good to know. I haven't converted my Kaweco to an eyedropper yet but it's on the to-do list.

  • Dan

    Thanks Brian, my Kaweco had a small leak that i couldn't find, now it is perfect

  • I'd love to say which inks are better suited, but it's not really something I've tested extensively. It's sort of like saying which inks will bleed on a given paper….it's not something you can really tell until you try it, and I haven't had a chance to try out a range of inks in the Kaweco eyedroppers yet. I have gotten some feedback from others who have done conversions with these pens and they've mentioned some inks not working as well, but after further talks, it seems like the bigger factor is how full the pen is. It seems like most inks (even 'stubborn' ones) will have a much lesser tendency to leak if the pen is kept more on the full side.

  • Perhaps I misspoke, I'm not really sure whether pressure inside of a pen drops or rises as you go up in a pressurized aircraft! I'm not much for the science of it, more for the practical aspects. Practically speaking, taking a fountain pen up in a plane increases the chance of leaking, for whatever reason 🙂 

  • Interesting, I didn't know that the pens could be affected that much just by elevation change! It kind of makes sense though, I guess. Keeping the nibs up (just like on the plane) should help with that next time 🙂 

  • Awesome! Glad it helped.

  • They're good pens for it, but any eyedropper pen is going to need a little caution. 

  • PurpleDrazi

    It's a matter of the relative difference in pressure between the air bubble inside the pen and air pressure outside the pen.

    In the case where the hand (or other stimulus) warms up the pen, the pressure in the air bubble inside the pens increases and pushes ink out.

    In the case of the airplane, the (outside of the pen) air pressure decreases. The air pressure inside the air bubble, while still the same, is now greater than the outside of the pen — and the ink gets pushed out

  • Emerrens

    great site and products.

    I did the Kaweko eyedropper conversion using silicone and still experienced leakage.  The leakage at the nib is not due to burping (although clearly this can happen) but is around the black plastic tube/housing in which the feed is fitting into (and clicks into in your followup troubleshooting video).  

    I think even in your original video you can see ink oozing from the chamber into this space by capillary action.  Of note, the top of this tube is not sealed, as it is not necessary when using cartridges.  

    The solution requires removing the nib and feed and carefully tapping the tube/housing out (while not damaging the small hole in which the nib feed enters.  

    Then you lube the outside of that tub/housing generously with silicone and reinsert until it clicks into place in the clear plastic front section and you're set to go.  reinsert the nib and feed ('click') and presto….no leakage.

  • Thank you for the very descriptive tip! I don't think I could have explained it better myself (though you wouldn't have had to if I had actually explained that myself!). I think this will help a bunch of folks out. 

  • Brian

    Any suggestions on what tool to use to tap the black housing out?

  • Nothing. I'd leave it in there. Taking it out doesn't buy you much, and it's way too easy to damage it, ruining the pen (I know from experience!).

  • Brian

    I'm having much trouble with ink leaking not from the tip of the nib or the threadings, but from the black housing tube, as Emerrens described, in two of my Sports. Changes in environmental temp seemed to trigger it, and sometimes just using it, which I attributed to my warm hands. I've had to un-convert these two pens from eyedropper back to cartridge; a bit annoying, since this was the main reason I purchased them (before I found this site). Any ideas on how to fix this, apart from the suggestion above? And thanks for this site — good info and good variety of pens.