Ancient Bronze vs Old Gold

How close are they?

ΔE 18.4, loose: different enough that you should pick on purpose. Old Gold is noticeably darker, more muted than Ancient Bronze.

Can I use Old Gold instead of Ancient Bronze?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Old Gold is noticeably darker, more muted than Ancient Bronze.

Can I use Ancient Bronze instead of Old Gold?

The same difference applies the other way round: Ancient Bronze 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.