Imp Yellow vs Sandy Yellow

How close are they?

ΔE 8.4, close: similar, with a visible difference side by side. Sandy Yellow is a little darker, more saturated than Imp Yellow.

Can I use Sandy Yellow instead of Imp Yellow?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Sandy Yellow is a little darker, more saturated than Imp Yellow.

Can I use Imp Yellow instead of Sandy Yellow?

The same difference applies the other way round: Imp Yellow is a little lighter, more muted.

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.