Matt Black vs Prusian Blue

How close are they?

ΔE 10.6, fair: the same colour family, but not a straight swap. Prusian Blue is a little lighter, more saturated than Matt Black.

Can I use Prusian Blue instead of Matt Black?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Prusian Blue is a little lighter, more saturated than Matt Black.

Can I use Matt Black instead of Prusian Blue?

The same difference applies the other way round: Matt Black is a little darker, 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.