RAF Sky / FS 34424 vs Underhive Ash

How close are they?

ΔE 5.5, very close: most people won’t see a difference side by side. Underhive Ash is a little darker, warmer than RAF Sky / FS 34424.

Can I use Underhive Ash instead of RAF Sky / FS 34424?

Yes, for most jobs. Very close match (ΔE 6). Underhive Ash is a little darker, warmer than RAF Sky / FS 34424.

Can I use RAF Sky / FS 34424 instead of Underhive Ash?

The same difference applies the other way round: RAF Sky / FS 34424 is a little lighter, 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.