Canoptek Alloy vs Iridescent Bronze (Fine)

How close are they?

ΔE 18.0, loose: different enough that you should pick on purpose. Iridescent Bronze (Fine) is noticeably darker, more saturated, warmer than Canoptek Alloy. They are different kinds of paint: Citadel Canoptek Alloy is a metallic and Golden Iridescent Bronze (Fine) is a pearl paint, so they won’t behave the same on the model even where the colour is close.

Can I use Iridescent Bronze (Fine) instead of Canoptek Alloy?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Iridescent Bronze (Fine) is noticeably darker, more saturated, warmer than Canoptek Alloy. They are different kinds of paint.

Can I use Canoptek Alloy instead of Iridescent Bronze (Fine)?

The same difference applies the other way round: Canoptek Alloy is noticeably lighter, more muted, cooler.

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.