Despite the fact that it is called "stainless" steel, this workhorse material for kitchen appliances and fixtures sometimes does not live up to its name. On a stainless steel kitchen sink, for example, you may have had a cleaning mishap that left brown stains on the metal. Stains can also sometimes result when a spray cleaner is applied to the metal but isn't rinsed away properly. And there are other mistakes you can make with stainless steel that can leave stains.
These stains can be stubborn, but there are ways to clean them away.
The Chemistry of Stainless Steel
The metal known as stainless steel is a steel alloy that contains a minimum of 10.5 percent chromium, measured by mass. The chromium lends the steel a degree of corrosion resistance (corrosion, or rust is the most common form of staining on steel). The degree of corrosion protection increases with the percentage of chromium in the alloy. Rather than oxidizing and discoloring when exposed to air or water, the chromium reacts to form a thin protective coating to the sink or other appliance. Although this protective layer can be scrubbed away, the protective film quickly reforms, which is why stainless steel surfaces are almost indestructible in a kitchen.
The fact that this alloy doesn't corrode and rust, along with the fact that it is self-healing when the protective film is scrubbed away, is why this material is known as stainless steel.
How to Remove Stains From Stainless Steel
Cleaning stainless steel can sometimes seem tricky since this shiny material can be scratched fairly easily. This is less problematic with a matte-finish surface, like that found on some sinks, but shiny stainless steel requires some care in order to remove stains without scratching the finish. Fortunately, stainless steel is a very resilient material that responds well to several different cleaning techniques.
First, examine your stainless steel surface and determine if it has a "grain" pattern. While the metal itself is solid, the process by which the manufacturer polished the surface may leave it with faint directional scratches. Whenever you scrub at a stainless steel surface—even if using so-called "non-scratch" pads—you should rub at the stains in the same direction as whatever grain is already present on the surface.
Here are four methods you can try for removing stains from stainless steel. Run through these solutions in order, as they are listed in order of how likely they are to damage the surface, with safest solutions first.
Many stains will be lifted from stainless steel by the action of steam vapors.
Heat water to boiling in a kettle with a spout that will allow you to pour it.
Place a paper towel or microfiber towel over the stained surface.
Pour enough of the boiling water onto the paper towel to wet it. Allow it to steam to work for five to ten minutes.
Once the surface has cooled, rub the surface with the paper towel, moving with the direction of the grain. If this doesn't remove the stain, try the next solution.
Baking Soda and Dish Soap
Baking soda mixed with liquid dish soap can make a good paste to gently rub out stains. Baking soda is a very fine abrasive that is unlikely to seriously scratch the stainless steel surface.
Apply the mixture of baking soda and liquid dish soap to a microfiber cloth or another soft cloth, then rub at the stain, moving back and forth in the same directions as the grain in the metal.
After scrubbing, rinse the stainless steel surface thoroughly, and towel it dry.
Examine the surface. If this hasn't removed the stain, try the next technique.
Pour a little white vinegar or apple cider vinegar onto the stained surface.
Let it sit for a few minutes; the gentle acid in the vinegar may lift out the stains.
Rub the stained with a soft cloth, following the grain of the steel.
Rinse thoroughly, and dry the surface with a clean towel.
Examine the stained area; if discoloration still is present, move on to the last solution.
Stainless Steel Cleaner