"Iron Mould" is a common term used to describe the reddish-brown rust spots that form on fabrics, walls and other surfaces due to prolonged exposure to moisture and humidity. There are several other synonyms for this term such as rust stains, iron stains, rust marks, iron oxide, and corrosion spots. These stains are quite common and can be difficult to remove, especially if they have been there for some time. Depending on the surface and the severity of the stains, there are several cleaning methods that one can use to remove iron mould. These include the use of vinegar, baking soda, hydrogen peroxide and specialized rust removers.