Vampire Fang vs IAF Sand

How close are they?

ΔE 7.6, close: similar, with a visible difference side by side. IAF Sand is a little darker, cooler than Vampire Fang.

Can I use IAF Sand instead of Vampire Fang?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). IAF Sand is a little darker, cooler than Vampire Fang.

Can I use Vampire Fang instead of IAF Sand?

The same difference applies the other way round: Vampire Fang 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.