Angelic Red vs Sekigahara

How close are they?

ΔE 24.6, loose: different enough that you should pick on purpose. Sekigahara is a little lighter, much more muted than Angelic Red.

Can I use Sekigahara instead of Angelic Red?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 25). Sekigahara is a little lighter, much more muted than Angelic Red.

Can I use Angelic Red instead of Sekigahara?

The same difference applies the other way round: Angelic Red is a little darker, much 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.