With piston fillers waterproof inks can be more cumbersome to clean out than the water soluble ones. Even if they are meant for fountain pens, others...
I don't have the need to use waterproof or semi-waterproof inks so wouldn't use any Noodlers ink in any of my TWSBI Diamond 580 pens. In fact I would...
There are literally thousands of fountain pen inks that are suitable for your TWSBI. Half of everyone who answers will give you their favourites. The...