Rust red
The red of corroded iron — the colour of strength that has been exposed to weather too long.
Rust red in a dream is the dream's image of the red of corroded iron, the colour of strength that has been exposed to water and air for too long. Rust is not a stain; it is the metal itself changing into something weaker. The dream brings rust when something in your life — a tool, a structure, a competence — has been used through seasons it was not protected against. A rust patch noticed and scraped off is the dream telling you the damage is being addressed. A rust that has eaten through the bar is the dream noting that the neglect has reached the point of structural failure, and the part will not bear the next weight.