Howdy! I know this is kind of a long shot, but Noodler's Black may have done in the diaphragm of my azure Parker Vacumatic (it's currently out to repair) and I was kind of hoping to find a water-resistant non-dangerous ink that more or less matches the pen's color (yeah, I'm one of those people). So I thought, hey, maybe a Diamine ink? I like teal blues--things in the ballpark Noodler's Texas Bluebonnet range. (I love that ink, but low-maintenance it is not.) Not keen on purply blues. Can live with blue-blacks/blue-grays. Right now I have determined that Diamine Prussian Blue will remain readable after a drop-water-on-it-wait-until-it-dries test. And, for kicks, Pilot Iroshizuku Tsuki-yo also seems to do about as well, so maybe that's an option. But I was wondering if anyone had suggestions for other things to try? If desperate I suppose I could consider Pilot Blue, which in my test had great water-resistance--I tried it and thought it was too faded purply-blue for my taste, but beggars can't be choosers.