ΔE 13.0, fair: the same colour family, but not a straight swap. Brown Beast Ink is noticeably darker, more muted, warmer than Strong Skin Wash. They are different kinds of paint: Army Painter Strong 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 13). Brown Beast Ink is noticeably darker, more muted, warmer than Strong Skin Wash. They are different kinds of paint.
The same difference applies the other way round: Strong Skin Wash is noticeably lighter, more saturated, 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 Strong Skin Wash on the colour wheel See Brown Beast Ink on the colour wheel
All matches: Strong Skin Wash equivalents · Brown Beast Ink equivalents