Kaweco fountain pens are ideal for eyedropper conversion. I can go on and on about it all, but I cover it pretty well in the video. I did mention in the video that you can refill your standard international cartridges (as an alternative to doing this eyedropper conversion), and I show you how to do that in this other video (at around 3 minutes in).
Since making this video, Kaweco has since released a mini piston-style cartridge converter to fit their Sport fountain pens. However, the ink capacity is pretty tiny compared to what you'll get with an eyedropper conversion.
Note: 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:
- 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.
- 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.
- 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, these pointers will help you to troubleshoot your Kaweco eyedropper conversion.