Loc: Perv Toy Row, San Francisco, C...
It doesn't set up hard like nail polish.
Dice, that is an interesting observation. I know a LOT of, especially, Atlas books from the 50's, often exhibit absolutely blinding richness of the inks. I tend to attribute this to an ink combination that had some VERY dense coverage (like a 100M/100C) etc. But adding the potentail for the inks to setup "hard like nail polish" makes me think back to my gem cutting days. The harder the stone, the brighter the polish. A soft stone never could really produce a mirror finish. Turquoise, for example, can be on the flat side. But the turquoise from tibet, where the mineral was impregnated with silicone, resulting in a very hard stone, took an amazing polish.
I have to wonder if this aspect of the ink's setup qualities, in combination with dense coverage, could have produced those incredibly deep and highly REFLECTIVE qualities?