Rust stain

countrycotton

So last week I stripped and sunned my diapers. I like to do this every few months as we have super hard well water. While sunning one of my elementals flew off the line and ended up landing on a old iron gate. I didn't notice when I gathered them up, it but when I was folding and putting away yesterday I found rust stains. I don't like elementals much and wanted to sell it soon. Is there any way to get the rust stain out? Or an I going to take a major resell hit on this one?

freezorburn

The google says lemon or vinegar + salt?