Phalanx Blue vs Sky Blue

How close are they?

ΔE 9.6, close: similar, with a visible difference side by side. Sky Blue is a little lighter, more saturated, warmer than Phalanx Blue.

Can I use Sky Blue instead of Phalanx Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Sky Blue is a little lighter, more saturated, warmer than Phalanx Blue.

Can I use Phalanx Blue instead of Sky Blue?

The same difference applies the other way round: Phalanx Blue is a little darker, more muted, cooler.

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.