Helmet Brown vs Gangrene

How close are they?

ΔE 9.9, close: similar, with a visible difference side by side. Gangrene is a little darker, more saturated than Helmet Brown.

Can I use Gangrene instead of Helmet Brown?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Gangrene is a little darker, more saturated than Helmet Brown.

Can I use Helmet Brown instead of Gangrene?

The same difference applies the other way round: Helmet Brown is a little lighter, 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.