ΔE 9.8, close: similar, with a visible difference side by side. Barley Gray BS4800/18B21 is more saturated than Typhon Ash.
Usually, if you are not matching paint already on the model. Close match (ΔE 10). Barley Gray BS4800/18B21 is more saturated than Typhon Ash.
The same difference applies the other way round: Typhon Ash 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.
See Typhon Ash on the colour wheel See Barley Gray BS4800/18B21 on the colour wheel
All matches: Typhon Ash equivalents · Barley Gray BS4800/18B21 equivalents