ΔE 10.2, fair: the same colour family, but not a straight swap. Brown Beast Ink is a little darker, more saturated, warmer than Dark Skin Wash. They are different kinds of paint: Army Painter Dark Skin Wash is a wash/shade and Nocturna Models Brown Beast Ink is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Brown Beast Ink is a little darker, more saturated, warmer than Dark Skin Wash. They are different kinds of paint.
The same difference applies the other way round: Dark Skin Wash is a little lighter, more muted, cooler.
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.
See Dark Skin Wash on the colour wheel See Brown Beast Ink on the colour wheel
All matches: Dark Skin Wash equivalents · Brown Beast Ink equivalents