Mechanicus Standard Grey vs Abyssal Blue

How close are they?

ΔE 11.7, fair: the same colour family, but not a straight swap. Abyssal Blue is noticeably darker than Mechanicus Standard Grey.

Can I use Abyssal Blue instead of Mechanicus Standard Grey?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Abyssal Blue is noticeably darker than Mechanicus Standard Grey.

Can I use Mechanicus Standard Grey instead of Abyssal Blue?

The same difference applies the other way round: Mechanicus Standard Grey is noticeably lighter.

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.