Field Grey FS-34159 vs Dawnstone

How close are they?

ΔE 9.1, close: similar, with a visible difference side by side. Dawnstone is a little lighter, more muted than Field Grey FS-34159.

Can I use Dawnstone instead of Field Grey FS-34159?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Dawnstone is a little lighter, more muted than Field Grey FS-34159.

Can I use Field Grey FS-34159 instead of Dawnstone?

The same difference applies the other way round: Field Grey FS-34159 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.