A fairly common phenomenon when stainless steel is not regularly maintained is the appearance of stains resembling a rusty color. In most cases, this is environmental deposit (most commonly road salt, metal filings, bird droppings, equipment contaminants, construction dust), which, without systematic care, can superficially react and damage the passive layer. To remove stains, use appropriate stainless steel cleaning products, such as those from WURTH or 3M.

The properties of stainless steel (including surface porosity) cause deposits of various types of contaminants to adhere more permanently to its surface than deposits on painted or galvanized surfaces, for example.