Doombull Brown vs Deep Scarlet Ink

How close are they?

ΔE 21.1, loose: different enough that you should pick on purpose. Deep Scarlet Ink is noticeably darker, more muted, cooler than Doombull Brown. They are different kinds of paint: Citadel Doombull Brown is an opaque base/layer paint and Nocturna Models Deep Scarlet Ink is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.

Can I use Deep Scarlet Ink instead of Doombull Brown?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Deep Scarlet Ink is noticeably darker, more muted, cooler than Doombull Brown. They are different kinds of paint.

Can I use Doombull Brown instead of Deep Scarlet Ink?

The same difference applies the other way round: Doombull Brown is noticeably lighter, 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.