Mephiston Red vs Blood Red

How close are they?

ΔE 9.1, close: similar, with a visible difference side by side. Blood Red is more muted, cooler than Mephiston Red.

Can I use Blood Red instead of Mephiston Red?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Blood Red is more muted, cooler than Mephiston Red.

Can I use Mephiston Red instead of Blood Red?

The same difference applies the other way round: Mephiston Red is 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.