Home >> Science & Nature >> Science

What Is Flash Rusting?

Flash rust will appear quickly and can contaminate any metallic surface, most notably steel. Flash rust appears when iron ore particles interact with moisture on the surface of metal. Sometimes, however, flash rust bleeds through the protective coating applied to a metal -- usually within hours of applying the coating -- because there was a thin layer of moisture on the metal before the application of the coating. Flash rusting in not long-term corrosion, unless it continues to be neglected.

Preventing Flash Rust
- To prevent flash rust from appearing on metal, a protective coating is important, but you must apply it with a rust inhibitor. Without an inhibitor, water-soluble particles can migrate to the surface and cause flash rust. Examples of a flash rust inhibitors include a variety of products, of which the most widely used is the Flash X-150 product. It is a nitrate-based solution that is mixed right in the can during the manufacturing of the protective coating. If a protective coating does not have a flash rust inhibitor, you should not use it. Those that do will have it clearly annotated on the can. Make sure you use a rag to completely dry the metal before applying the coating.
Stopping Flash Rust
- Flash rust caused by iron ore particles depositing on the surface will require maintenance. In such cases, you will need to clean the rust from the surface. Use a rust cleaner -- there are quite a few on the market -- and clean the surface, using steel wool to scrub the rust off. After you clean the surface, you should apply the protective coating with a rust inhibitor to help stop future flash rusting.
Problems with Aerosols
- Primarily in coastal areas, flash rusting can also appear due to evaporation of saltwater, which the wind deposits on metal in the form of salt and chloride. These are called aerosols. The effects of this evaporation are far worse than the effects of seawater coming in contact with the metal. It will leave surface rust on the metal, appearing almost overnight. Cleaning the metal and using a protective coating with a rust inhibitor can still reverse the process and help prevent future flash rust.
Contact Flash Rust
- Flash rust can also appear due to contact corrosion. For example, contact between carbon steel and stainless steel will cause flash rust on the stainless steel. The best way to prevent this situation is not to mix carbon and stainless steel. However, this is not always an option. You will need to regularly clean the stainless steel surface in these cases.

Science