Rough Iron vs Oily Steel

How close are they?

ΔE 6.1, close: similar, with a visible difference side by side. Oily Steel is more saturated than Rough Iron.

Can I use Oily Steel instead of Rough Iron?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Oily Steel is more saturated than Rough Iron.

Can I use Rough Iron instead of Oily Steel?

The same difference applies the other way round: Rough Iron 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.