A stainless steel skillet is nonporous and generally dishwasher safe. But, depending on the skillet's handle and bottom coating, it's often best to wash by hand using hot water and liquid dish soap. For stubborn stains, use a scouring powder, meshed scrubber or stiff brush. Dry the pan thoroughly before storing.
Avoid overheating a stainless steel skillet to keep blue blotches from appearing on the surface. The spots are difficult to remove and may cause permanent discoloration. The pan, however, is still safe to use.
If the stainless steel skillet has a copper bottom, the copper will darken and discolor during use. While a dull copper bottom transfers heat better than shiny copper, many consumers opt for shiny -- especially when the copper-bottomed skillet hangs on a pot rack. To get the copper bottom shiny, scrub with table salt moistened with white distilled vinegar or lemon. There are also copper scouring powders on the market.
When the stainless steel skillet has an aluminum bottom, the aluminum can discolor over time. After washing the skillet, turn it upside down on the counter. Cut a lemon in half, sprinkle with a liberal amount of salt and scrub the aluminum bottom to remove discoloration. Do not rub too hard -- salt is abrasive and may scratch the surface. Rinse the pan thoroughly and dry before storing.