Foundry Red vs Ruby Red

How close are they?

ΔE 7.6, close: similar, with a visible difference side by side. Ruby Red is more muted than Foundry Red.

Can I use Ruby Red instead of Foundry Red?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Ruby Red is more muted than Foundry Red.

Can I use Foundry Red instead of Ruby Red?

The same difference applies the other way round: Foundry Red 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.