Because of all the questions around some inks possibly causing rubber sacs to fail prematurely, I have decided to conduct a series of methodical tests using my bulb-filler pens. Because these pens use rubber bulbs, but the bulbs are quite easy and inexpensive for me to replace as needed, they're ideal for testing inks that might possibly be "dangerous" to latex rubber.
The methodology I've decided on is. . . Ink one pen each month, and use it continually with the chosen ink for three months. At the end of that time, check the bulb carefully for evidence of decay. Because I have three bulb-fillers, using all of them will give me one test result per month. (Obviously I expect to be doing this for A While.) I also decided to only flush them with distilled water, to rule out any possible contaminants in the tap water here.
If anybody else would like to join in and report your results too, that would be OK. I'd only suggest following a similar regimen, if you can, so that our results can be compared on a somewhat even basis.
The first pen in the series is my Edison Morgan, which I inked a month ago with Montblanc Midnight Blue. Because of its huge ink capacity, I've used less than half the fill, and it's still going strong.
Today I tanked up the second pen, my Edison Glenmont, with that most iconic ink: Noodler's Black.
Next will be the Gate City New Postal Jr., and I have a month to decide what ink to put in that. I also need to get another new bulb for it. I've already installed a fresh bulb, but it seems to be too small, and it doesn't displace enough air to fully fill the pen. So, I'll try a bigger one and see how that goes.