Iridescent Copper (Fine) vs Light Brown

How close are they?

ΔE 6.5, close: similar, with a visible difference side by side. Light Brown is more muted than Iridescent Copper (Fine). They are different kinds of paint: Golden Iridescent Copper (Fine) is a pearl paint and Vallejo Light Brown is an opaque base/layer paint, so they won’t behave the same on the model even where the colour is close.

Can I use Light Brown instead of Iridescent Copper (Fine)?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Light Brown is more muted than Iridescent Copper (Fine). They are different kinds of paint.

Can I use Iridescent Copper (Fine) instead of Light Brown?

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