Interference Blue (Fine) vs Interference Violet (Fine)

How close are they?

ΔE 6.9, close: similar, with a visible difference side by side. Interference Violet (Fine) is cooler than Interference Blue (Fine).

Can I use Interference Violet (Fine) instead of Interference Blue (Fine)?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Interference Violet (Fine) is cooler than Interference Blue (Fine).

Can I use Interference Blue (Fine) instead of Interference Violet (Fine)?

The same difference applies the other way round: Interference Blue (Fine) is 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.