Baharroth Blue vs Primary Blue

How close are they?

ΔE 8.7, close: similar, with a visible difference side by side. Primary Blue is more saturated than Baharroth Blue.

Can I use Primary Blue instead of Baharroth Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Primary Blue is more saturated than Baharroth Blue.

Can I use Baharroth Blue instead of Primary Blue?

The same difference applies the other way round: Baharroth Blue is more muted.

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.