Under normal circumstances, stainless steel countertops will not stain. Stainless steel is impervious to the common sources of kitchen stains such as oil, food ingredients, and blood from meats. It is nonporous, prevents the accumulation of soap scum, and does not harbor the growth of bacteria, molds, and mildew.|
However, stainless steel countertops can discolor if they are not maintained properly. Here is a quick guide on how to keep them from staining and maintain their shiny surface:
Acids are commonly used on stainless steel countertops for making additional detailing and edge designs. The acid eats away at the protective layer of chromium oxide, the material that gives stainless steel its distinct sheen and remarkable characteristics. These are generally weak acids, consisting of only little amounts of ascetic or citric acid. The problem with detailing stainless steel countertops using acid is that there is a thin line between giving them an attractive design and ruining them completely. Acids that are too strong can erode too much of the chromium and expose the metal underneath to environmental damage. On the other hand, acids that are too weak cannot leave any recognizable detailing on the countertop.
Acidic cleansers are commonly used for cleaning swimming pools and bathroom tiles. Hydrochloric acid breaks down mold and mildew that accumulate in between the tiles or along the tile grout. However, it should not be used on stainless steel countertops because hydrochloric acid can definitely ruin the finish of the countertops. The acid can potentially eat right through the chromium oxide skin and expose the base steel to water damage. Water damage is steel's number one enemy when it comes to stains.
Steel brushes and abrasives
While stainless steel is significantly more scratch-resistant than plain carbon steel, constantly scrubbing stainless steel countertops with steel wool or brushes with steel bristles can tear away the chromium oxide layer. People who use these highly abrasive cleaning tools on stainless steel countertops often find that little bits and flecks of metal come away with the tools with each scrub. These flecks are actually the chromium oxide skin. If this cleaning method is done long enough, the steel underneath can eventually be worn away as well.
How stainless steel stains
Stainless steel countertops can rust if they are not properly cared for. Rusting can occur in two ways: when the chromium oxide skin is stripped off and when naked steel comes in contact with water.
When a drop of water comes in contact with air, it reacts to the carbon dioxide present in it and forms a weak carbonic acid as a result. When the carbonic acid makes contact with the steel, the carbon present in the steel reacts to it until the iron is exposed. The acid continues to break down the iron as water breaks down into its component hydrogen and oxygen bases. Oxygen combines with the iron to form iron oxide or rust.