Tyrant Skull vs Birch

How close are they?

ΔE 8.1, close: similar, with a visible difference side by side. Birch is a little lighter, warmer than Tyrant Skull.

Can I use Birch instead of Tyrant Skull?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Birch is a little lighter, warmer than Tyrant Skull.

Can I use Tyrant Skull instead of Birch?

The same difference applies the other way round: Tyrant Skull is a little darker, 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.