Calth Blue Clear vs Imperial Blue

How close are they?

ΔE 15.8, loose: different enough that you should pick on purpose. Imperial Blue is a little darker, much more muted than Calth Blue Clear.

Can I use Imperial Blue instead of Calth Blue Clear?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Imperial Blue is a little darker, much more muted than Calth Blue Clear.

Can I use Calth Blue Clear instead of Imperial Blue?

The same difference applies the other way round: Calth Blue Clear is a little lighter, much more saturated.

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.