MiG-25/MiG-31 Grey vs Ulthuan Grey

How close are they?

ΔE 9.0, close: similar, with a visible difference side by side. Ulthuan Grey is more saturated than MiG-25/MiG-31 Grey.

Can I use Ulthuan Grey instead of MiG-25/MiG-31 Grey?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Ulthuan Grey is more saturated than MiG-25/MiG-31 Grey.

Can I use MiG-25/MiG-31 Grey instead of Ulthuan Grey?

The same difference applies the other way round: MiG-25/MiG-31 Grey is 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.