Daemonic Yellow vs Primary Yellow

How close are they?

ΔE 7.4, close: similar, with a visible difference side by side. Primary Yellow is a little lighter than Daemonic Yellow.

Can I use Primary Yellow instead of Daemonic Yellow?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Primary Yellow is a little lighter than Daemonic Yellow.

Can I use Daemonic Yellow instead of Primary Yellow?

The same difference applies the other way round: Daemonic Yellow is a little darker.

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.