I keep forgetting how people on this forum love to nitpick for the sake of nitpicking.
Let me rephrase my questions. Perhaps a bit of clarification with help garner some actual answers -- or maybe just fuel a couple new reasons to disagree.
What inks tend to leave a stain after you've used attempted to clean out your pen with a basic rinsing of room temperature distilled water that is brought into and expelled from the pen using the pens own filling system, bulb syringe or needle and syringe, but NOT with an ultrasonic cleaner, bleach, pen flush, vinegar, turpentine, red ink, tarter sauce, Zout, Oxyclean or other chemical or natural additive.
What inks have you heard can cause a rubber sac to weaken / melt / corrode / granulate / harden / or other chemical reaction that could lead to ink dripping, leaking, squirting, sweating or any other method that causes ink to leave the sac and get all over the inside of a pen?
Perhaps the only frustrating thing about FPN is how people contradict others when they have little in the way of information and argue with what others say based on their own experience.
I have only had two problem inks.
Diamine Grape went straight through a Duofold, a drop of ink per second came through the nib, not sure what was going on there.
I used (a seperate bottle) of Diamine Grape and MB Lavendar in a Montblanc 146, the flow was terrible. Took it into MB for servicing and they said that the window had become stained, they asked if I had been using Diamine inks, I lied.
Had a good look at the MB ink and it had seperated, clear liquid above a gelatinous liquid. I dipped a pencil into the ink and it left a long gooey trail from the bottle
MB replaced the barrel, I would expect that they would have tried to clean it first and failed presumably. I havent used Diamine Reds, Blues or Purples since then, or MB Lavendar for that matter.