A coating of iron oxide (4)
I believe the answer is:
rust
(Other definitions for rust that I've seen before include "Corrode" , "Fungal plant disease" , "Reddish-brown coating formed on metal by damp" , "Reddish-brown colour" , "deteriorate" .)
I believe the answer is:
rust
(Other definitions for rust that I've seen before include "Corrode" , "Fungal plant disease" , "Reddish-brown coating formed on metal by damp" , "Reddish-brown colour" , "deteriorate" .)