Underhive Ash vs Medium Sea Gray

How close are they?

ΔE 6.1, close: similar, with a visible difference side by side. Medium Sea Gray is more muted than Underhive Ash.

Can I use Medium Sea Gray instead of Underhive Ash?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Medium Sea Gray is more muted than Underhive Ash.

Can I use Underhive Ash instead of Medium Sea Gray?

The same difference applies the other way round: Underhive Ash is 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.