Runelord Brass vs Red Goblin

How close are they?

ΔE 22.3, loose: different enough that you should pick on purpose. Red Goblin is more muted, cooler than Runelord Brass.

Can I use Red Goblin instead of Runelord Brass?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Red Goblin is more muted, cooler than Runelord Brass.

Can I use Runelord Brass instead of Red Goblin?

The same difference applies the other way round: Runelord Brass is more saturated, warmer.

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.