Orc Blood vs Decadent Purple

How close are they?

ΔE 7.4, close: similar, with a visible difference side by side. Decadent Purple is a little darker, cooler than Orc Blood.

Can I use Decadent Purple instead of Orc Blood?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Decadent Purple is a little darker, cooler than Orc Blood.

Can I use Orc Blood instead of Decadent Purple?

The same difference applies the other way round: Orc Blood is a little lighter, warmer.

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.