Rust Staining


Definition - What does Rust Staining mean?

Rust staining refers to the occurrence of a paint defect that is due to the discoloration of an applied coating on a substrate. The discoloration occurs due to the accumulation of reddish colored iron oxide deposits. Such paints are applied to metal surfaces as protection against corrosion.

Corrosionpedia explains Rust Staining

Rust staining is caused by dissolved minerals or salts that remain after electrochemical corrosion reactions have occurred.

Rust staining is more likely to occur where hard water exists because it contains significantly higher levels of minerals compared to soft water and distilled water. The primary natural source of hard water is rainwater. Rainwater falls as soft water from clouds; however as it descends it accumulates lime, chalk and other substances that contribute to its increased hardness.

Rust staining can be prevented by the following methods:

  • Using structural designs that reduce moisture capture
  • Using dark colored coatings that hide signs of impurities
  • Chemical washing the affected surfaces as a preventative approach

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