Except for my Recife Crystal pens (which have been leak-free from the start), I’ve had a major problem with ink-burping with almost all of the eyedroppers I’ve purchased over the years. I’ve switched out nibs and feeds on some of them using ones from NoNonesense pens makes a difference, but only in a few cases. Warming the pen by holding it upright also helps a bit, but I often want simply to grab a pen and write without waiting; and some of my pens still burped anyway. Topping off the pen with ink helps, though I rotate pens frequently and would prefer not to keep a large-capacity pen filled just so I can use it. Of course, this may mean that eyedroppers aren’t for me; I admit that I’m being stubborn. In any case, after reading about the Pilot Tank eyedropper that has an insert to lessen its ink capacity-- http://www.fountainp...ive-pilot-tank/ --I decided to try that approach.
I hunted around a while and finally settled on small plastic beads. I was assuming that they’d be pretty stable when exposed to ink. Also, I could easily adjust the given pen's capacity. Besides, the clear ones would look cool in transparent barrels. Here’s an example of what I’ve been using (no connex to the vendor):
I wonder if the fact that the beads are pierced makes a difference—I suspect not. In fact, I’m not at all certain that this strategy is a guaranteed fix; however, it seems to be curbing the leak-problem in several eyedroppers that I’ve not been able to use previously.