Mephiston Red vs Alizarin Crimson Hue

How close are they?

ΔE 15.4, loose: different enough that you should pick on purpose. Alizarin Crimson Hue is a little darker, more muted, cooler than Mephiston Red.

Can I use Alizarin Crimson Hue instead of Mephiston Red?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Alizarin Crimson Hue is a little darker, more muted, cooler than Mephiston Red.

Can I use Mephiston Red instead of Alizarin Crimson Hue?

The same difference applies the other way round: Mephiston Red is a little lighter, more saturated, 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.