Weird Elixir vs Smalt Hue

How close are they?

ΔE 34.9, loose: different enough that you should pick on purpose. Smalt Hue is a little darker, cooler than Weird Elixir.

Can I use Smalt Hue instead of Weird Elixir?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 35). Smalt Hue is a little darker, cooler than Weird Elixir.

Can I use Weird Elixir instead of Smalt Hue?

The same difference applies the other way round: Weird Elixir 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.