Depending on the type of water you use with your steam iron, minerals in that water crystallize, clogging the steam ports and creating a rough build-up on the iron's face. Over time this mineral residue on the face of the iron, if not cleaned off, discolors the clothes the iron is used on, leaving permanent stains on anything the iron touches. You can clean the minerals from the face of the steam iron to make the iron work like new and save clothes from ruinous stains.
Scrape as much build-up as possible from the face of the iron using a blunt tipped butter knife.
Clean the steam jets on the face of the iron with a pin or needle to ensure they are all open and working.
Fill the steam reservoir with equal parts vinegar and distilled water, then plug the iron in, set it to steam and let the iron emit steam until all the vinegar water mixture has evaporated.
Fill the reservoir with clean water.
Test the iron on a clean, dry, white cloth to ensure that the face of the iron moves over the cloth without catching or sticking, indicating that all build-up or residue is gone, and that there is no staining left behind from contact with the iron's face.