Flash Rust: (1) An oxidation product that forms as a wetted carbon steel substrate dries;

(2) Appearance of rust spots on the surface of newly-applied water-borne film during the drying phase.  This is different than Rust Back.

Rust Bloom (from NACE/ASTM Glossary): discoloration indicating the beginning of rusting.

Rust-Back (rerusting) is rusting that occurs when freshly exposed, dry, bare steel is exposed to conditions of high humidity, moisture, or a corrosive atmosphere. It is the term used when steel cleaned by dry abrasive blasting, power tools, or wet abrasive blasting begins to rust after the steel surface has completely dried.