Iridescent Copper (Fine) vs Forged Red

How close are they?

ΔE 21.3, loose: different enough that you should pick on purpose. Forged Red is noticeably lighter, more saturated than Iridescent Copper (Fine). They are different kinds of paint: Golden Iridescent Copper (Fine) is a pearl paint and Vallejo Forged Red is a metallic, so they won’t behave the same on the model even where the colour is close.

Can I use Forged Red instead of Iridescent Copper (Fine)?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Forged Red is noticeably lighter, more saturated than Iridescent Copper (Fine). They are different kinds of paint.

Can I use Iridescent Copper (Fine) instead of Forged Red?

The same difference applies the other way round: Iridescent Copper (Fine) 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.