Stormfang vs Medium Gray

How close are they?

ΔE 7.8, close: similar, with a visible difference side by side. Medium Gray is a little lighter, more muted, cooler than Stormfang.

Can I use Medium Gray instead of Stormfang?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Medium Gray is a little lighter, more muted, cooler than Stormfang.

Can I use Stormfang instead of Medium Gray?

The same difference applies the other way round: Stormfang is a little darker, more saturated, 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.