Stonewall Grey vs Saddle Brown

How close are they?

ΔE 6.6, close: similar, with a visible difference side by side. Saddle Brown is more saturated, warmer than Stonewall Grey.

Can I use Saddle Brown instead of Stonewall Grey?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Saddle Brown is more saturated, warmer than Stonewall Grey.

Can I use Stonewall Grey instead of Saddle Brown?

The same difference applies the other way round: Stonewall Grey is more muted, 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.