How to Prevent Flash Rust

by Carole Ellis

Flash rust is rust that appears quickly--literally overnight--and can occur on any surface including stainless steel. Generally, flash rust is a result of small iron particles that have become lodged on another metal surface. When moistened, these iron particles rust very quickly and create a spotty film of rust in the area they have affected. Fortunately, preventing flash rust is a simple issue of time management in nearly all cases.

Remove any sources of potential "contamination." Often flash rust occurs on supposedly "rust-proof" metals because a metal that is susceptible to rust has been in contact with it. For example, non-galvanized screws can rust and spread that rust to stainless steel items. If you are having a problem with flash rust, then you need to look for sources of iron particle contamination and remove them to prevent further rusting.

The best way to prevent flash rust is to fully eliminate any present sources. This means you need to get rid of all the embedded iron particles and remove any existing rust. Use a damp cloth and 2 drops of mild detergent to scrub down the entire metal area to remove all dirt and grime. After you have cleaned the area with soap and water, remove the rust using steel wool.

Wipe down the entire area with clean water. This will help verify that all the rust is gone. However, if you stop now, the flash rust can actually reappear in the next few hours. You must take preventative steps immediately to stop this. Do not allow the metal to air-dry; wipe it down with a clean, dry rag immediately.

Scuff the metal surface. This will make it more receptive to the primer you are about to apply. Use sandpaper to scuff up the surface. Apply light pressure, as it is not necessary to make deep scratches.

Put on protective gloves and apply self-etching epoxy primer. The primer will remove any rust you missed while priming the metal for a coat of paint and preventing further flash rust. You can spray on the primer, paint it on, or apply it using a clean rag. Use two thin, even coats and allow the primer to dry completely (about 45 to 90 minutes) between applications. Once you have primed the metal, you have effectively prevented any existing iron particles from contributing to further flash rust. You will need to paint the metal to give it a good finish, but you can do this at a later time. Be sure that all sources of rust contamination stay away from the metal or they will deposit new iron particles.

Warning

  • close Always protect your skin when using chemicals like self-etching epoxy primers.

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About the Author

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