Phantasmal Blue vs Ray Gun Glow

How close are they?

ΔE 7.8, close: similar, with a visible difference side by side. Ray Gun Glow is more muted, cooler than Phantasmal Blue.

Can I use Ray Gun Glow instead of Phantasmal Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Ray Gun Glow is more muted, cooler than Phantasmal Blue.

Can I use Phantasmal Blue instead of Ray Gun Glow?

The same difference applies the other way round: Phantasmal Blue 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.