Grim Rust vs Light Brown

How close are they?

ΔE 8.2, close: similar, with a visible difference side by side. Light Brown is cooler than Grim Rust. They are different kinds of paint: Army Painter Grim Rust is a fluorescent or effect paint and Green Stuff World Light Brown is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.

Can I use Light Brown instead of Grim Rust?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Light Brown is cooler than Grim Rust. They are different kinds of paint.

Can I use Grim Rust instead of Light Brown?

The same difference applies the other way round: Grim Rust is warmer.

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.