Desert Skin vs Blackert Brown

How close are they?

ΔE 8.4, close: similar, with a visible difference side by side. Blackert Brown is a little lighter, more muted than Desert Skin.

Can I use Blackert Brown instead of Desert Skin?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Blackert Brown is a little lighter, more muted than Desert Skin.

Can I use Desert Skin instead of Blackert Brown?

The same difference applies the other way round: Desert Skin 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.