Griffon Blue vs Blue Base

How close are they?

ΔE 9.7, close: similar, with a visible difference side by side. Blue Base is a little darker, warmer than Griffon Blue.

Can I use Blue Base instead of Griffon Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Blue Base is a little darker, warmer than Griffon Blue.

Can I use Griffon Blue instead of Blue Base?

The same difference applies the other way round: Griffon Blue is a little lighter, 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.