Iron Fist vs Hammered Copper

How close are they?

ΔE 23.0, loose: different enough that you should pick on purpose. Hammered Copper is noticeably lighter, more saturated than Iron Fist.

Can I use Hammered Copper instead of Iron Fist?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). Hammered Copper is noticeably lighter, more saturated than Iron Fist.

Can I use Iron Fist instead of Hammered Copper?

The same difference applies the other way round: Iron Fist is noticeably 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.