Eternal Hunt vs Mortarion Green Clear

How close are they?

ΔE 9.6, close: similar, with a visible difference side by side. Mortarion Green Clear is a little lighter, warmer than Eternal Hunt.

Can I use Mortarion Green Clear instead of Eternal Hunt?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Mortarion Green Clear is a little lighter, warmer than Eternal Hunt.

Can I use Eternal Hunt instead of Mortarion Green Clear?

The same difference applies the other way round: Eternal Hunt is a little darker, cooler.

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.