Kakophoni Purple vs Cygnar Blue Base

How close are they?

ΔE 27.9, loose: different enough that you should pick on purpose. Cygnar Blue Base is a little darker, cooler than Kakophoni Purple.

Can I use Cygnar Blue Base instead of Kakophoni Purple?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 28). Cygnar Blue Base is a little darker, cooler than Kakophoni Purple.

Can I use Kakophoni Purple instead of Cygnar Blue Base?

The same difference applies the other way round: Kakophoni Purple is a little lighter, 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.