Rust, oils and verdigris

Rust starts as texture, not colour. I stipple a rough orange-brown over the metal first, then break it up with sponge-applied darker browns so it never looks like a flat wash.

Oil washes pull everything together: a thinned raw-umber filter knocks back the contrast, then pin washes settle into the rivets and seams.

Verdigris goes last, stippled sparingly where water would actually collect on brass. A little goes a long way — too much and it stops reading as corrosion.