I've subscribed to a quarterly modeling magazine called Sky Models. It's offered through Squadron- pretty good with lots of color photos. The Italian to English translation is a bit clunky at times but not a problem.
Anyway, one of the articles mentioned that the author thinned sepia colored ink with water and MILK before applying it to panel lines.
I did try thinning some acrylic ink with a 50/50 mix of water and 1% lowfat milk. It seemed that this slowed the drying time down for the ink and prevented staining of the painted surface. Has anyone else ever heard of or tried this combination?
Lee