Underhive Ash vs Donkey Grey

How close are they?

ΔE 7.6, close: similar, with a visible difference side by side. Donkey Grey is a little lighter, more muted than Underhive Ash.

Can I use Donkey Grey instead of Underhive Ash?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Donkey Grey is a little lighter, more muted than Underhive Ash.

Can I use Underhive Ash instead of Donkey Grey?

The same difference applies the other way round: Underhive Ash is a little darker, more saturated.

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.