Sacred Scarlet vs Orange

How close are they?

ΔE 7.2, close: similar, with a visible difference side by side. Orange is a little darker, more saturated than Sacred Scarlet.

Can I use Orange instead of Sacred Scarlet?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Orange is a little darker, more saturated than Sacred Scarlet.

Can I use Sacred Scarlet instead of Orange?

The same difference applies the other way round: Sacred Scarlet is a little lighter, more muted.

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.