Old Brass vs Obsidian Black

How close are they?

ΔE 10.5, fair: the same colour family, but not a straight swap. Obsidian Black is noticeably lighter than Old Brass.

Can I use Obsidian Black instead of Old Brass?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Obsidian Black is noticeably lighter than Old Brass.

Can I use Old Brass instead of Obsidian Black?

The same difference applies the other way round: Old Brass is noticeably darker.

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.