Ratling Grime vs Zombie Skin

How close are they?

ΔE 17.4, loose: different enough that you should pick on purpose. Zombie Skin is noticeably lighter, more saturated than Ratling Grime.

Can I use Zombie Skin instead of Ratling Grime?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Zombie Skin is noticeably lighter, more saturated than Ratling Grime.

Can I use Ratling Grime instead of Zombie Skin?

The same difference applies the other way round: Ratling Grime is noticeably darker, 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.