Obsidian Pigment Toner vs Oxidation Green

How close are they?

ΔE 6.5, close: similar, with a visible difference side by side. Oxidation Green is a little lighter, cooler than Obsidian Pigment Toner.

Can I use Oxidation Green instead of Obsidian Pigment Toner?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Oxidation Green is a little lighter, cooler than Obsidian Pigment Toner.

Can I use Obsidian Pigment Toner instead of Oxidation Green?

The same difference applies the other way round: Obsidian Pigment Toner is a little darker, warmer.

ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.