Nether Quartz seems a bit too expensive for white dye, as you need to go to the Nether for it. I think saltpeter would fit, what do you think?

White ink has been removed in the latest version, commit 344a1db, due to vanilla adding 3 methods of getting white dye besides killing skeletons - using their composter to make bone meal, mining fossils in the nether, and the lily of the valley flower.

Fair enough. Nether quartz was kind of just a "it's white-ish so I guess that works" sort of thing because vanilla Minecraft doesn't have a source of white pigment (titanium, lead, zinc, lime/chalk).

Saltpeter IRL cannot be used to make dye. Why not some other pigment in the overworld?

https://en.wikipedia.org/wiki/List_of_inorganic_pigments#White_pigments

@Sunconure11, any suggestions for which white pigment should be added and how? I couldn't figure out how to do it without adding something to worldgen.

Why not have it obtained in a fashion similar to mining sulfur and saltpeter, except from stone? To compensate, it should be fairly rare.

Or even a process something like this: https://en.wikipedia.org/wiki/Zinc_oxide#Production

While I think adding drops to other blocks is an okay solution, I don't want to overdo it, and stone already has a rare drop of bones. I also would like to avoid adding something that is only used for a single recipe and has little use outside of that.

Would it be acceptable to keep the current nether quartz recipe as the only recipe when VO is installed on its own, and then rely on other mods to supply other, easier, forms of white pigment (titanium/zinc/lead/etc)?

That could work. You could try maybe oxeyes or some other white flower.

Okay, maybe I'm late to the party here, but Titanium/Zinc could be a drop from Iron Ore... now to find another use for it. Maybe it could be used in the crafting of Encrusted Obsidian?

That might be a good idea.

Instead of coming up with a recipe to make white dye, would it be possible to just come up with some kind of bleach recipe, which can then be used on existing dyes to make them white? Maybe use redstone as a recipe for some crude electrolysis tech to produce hydrogen peroxide from water and air?

H2O (Water) + 2O2 (2 molecules of Air) ---> H2O2 (Hydrogen Peroxide) + O3 (Ozone)

The end result is hydrogen peroxide, as well as a temporary sense of nausea (recognizable to anyone who ever smelled ozone).

I like idea of Titanium or Zinc being drops from ores rarely.