True Copper vs Old Copper

How close are they?

ΔE 12.1, fair: the same colour family, but not a straight swap. Old Copper is noticeably darker, more muted than True Copper.

Can I use Old Copper instead of True Copper?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Old Copper is noticeably darker, more muted than True Copper.

Can I use True Copper instead of Old Copper?

The same difference applies the other way round: True Copper is noticeably lighter, 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.