Naggaroth Night vs Phthalo Blue (Red Shade)

How close are they?

ΔE 13.9, fair: the same colour family, but not a straight swap. Phthalo Blue (Red Shade) is noticeably darker, more muted, cooler than Naggaroth Night. They are different kinds of paint: Citadel Naggaroth Night is an opaque base/layer paint and Golden Phthalo Blue (Red Shade) 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 Phthalo Blue (Red Shade) instead of Naggaroth Night?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Phthalo Blue (Red Shade) is noticeably darker, more muted, cooler than Naggaroth Night. They are different kinds of paint.

Can I use Naggaroth Night instead of Phthalo Blue (Red Shade)?

The same difference applies the other way round: Naggaroth Night 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.