I apologize to the sadists among us for not having a scan. These are colors I love but avoided because I'm still skittish from having some, what was for me, inspired writing disappear without a trace to an unexpected thunderstorm after leaving it by an open window. (The shameful ink in question: MB black). Also, the Noodler's colors are subtle and perfect just as they are so it'd be difficult to add some bulletproof ink to them without dramatically changing their murky, foreboding character.
The test: I forcefully ran water over the sheet of paper for about a minute rubbing it lightly in places. Then I took it out for a few minutes. Then I put it back under the faucet for another minute. Finally, I threw it on the floor and stepped on it a few times before letting it dry.
The results: all three inks left faint but legible residues. Although not always super-easy to read, that's only to be expected because my handwriting is never super-easy to read. Nightshade performed the best, leaving a fairly dark purple residue. Sequoia left a fainter violet residue. Cafe des Iles merely looked fainter and more coppery.
Note: Test was performed with a dipped fine point semi-flex Waterman 52. Text written as the nib was drying out was most difficult to read but still legible.
Actually, I could post photos for those who are skeptical, or otherwise interested.