I use Rapidographs a lot in my art, and the old bottle of Koh-i-noor ink that I've been using with them is close to running out. It's not the greatest ink for my purposes--the shellac that makes it waterproof also makes everything shiny, which shows up on scanned images. It's also not as water-resistant as I'd like, mostly due to a layer of ink sitting on top of the surface of the paper and running all over the place if I try to use some watercolors over it. The solution to that, and to a certain extent to the sheen as well, has been to erase over everything really well to rub off any extra ink.
I could just buy a new bottle, keep erasing over everything, and deal with the residual shinyness. However, I've also recently bought some very thin-tipped technical pens that I don't want to get clogged (which almost always spells death for the hair-masquerading-as-a-wire inside finer rapidographs,) so I've been thinking about buying a fountain pen ink anyhow.
Platinum Carbon Black seems to be the recommended ink for anyone doing watercolor washes over drawings, but I'm also intrigued by the almost-perfect performance of Noodler's Black, which seems to have the same issue as the ink I'm currently using (ink left on the surface of the paper runs with water.) Noodler's is also cheaper, so I have a couple unanswered questions before I go off buying anything.
- How does Platinum Carbon Black/Noodler's Black perform on watercolor paper? Most of the reviews I can find about water resistance are on printer or notebook paper, which don't have as much sizing as a sheet of hot press watercolor paper. I suspect Noodler's will do worse than normal because it binds to cellulose, but I'm particularly interested in what, if anything, changes with the Platinum Carbon.
- If you erase over Noodler's, does the residual surface ink just smear around, or does any of it come off with erasing?
- If you erase over Noodler's, is there any difference in water resistance?
- Does either ink perform poorly in technical pens?
- Is there any water-resistant ink I'm completely looking over? Preferably black, but if there's some incredibly waterproof red I'm missing I might as well add it to the list.
These are pretty specific to my situation and I might just have to get some samples to test things myself, but I figured I might as well ask around here first.