Sacred Scarlet vs Squig Orange

How close are they?

ΔE 9.5, close: similar, with a visible difference side by side. Squig Orange is more muted than Sacred Scarlet.

Can I use Squig Orange instead of Sacred Scarlet?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Squig Orange is more muted than Sacred Scarlet.

Can I use Sacred Scarlet instead of Squig Orange?

The same difference applies the other way round: Sacred Scarlet is 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.