Certain foods such as raw fish, onions and garlic can leave very unpleasant odors on the hands of those who must process them in the kitchen. One common home remedy to remove these strong odors suggests a cook rub his or her hands against something made from stainless steel, such as a kitchen faucet or a large spoon. This idea of using stainless steel to neutralize or remove food odors is the basis for an invention known as stainless steel soap.
A stainless steel soap bar is made from the same materials as any other stainless steel product, mainly iron and chromium. A bar of ordinary steel is formed into the shape of a standard soap bar, then clad in a thin layer of chromium, also known as chrome. This layer of chromium is what makes stainless steel so stain-resistant. Chromium does not form rust in the normal sense of the word, but it does form an oxide when it remains in contact with air and water. Some believe this oxide layer is responsible for the purported odor-removing properties of the stainless steel bar.
Another theory suggests that the physical act of scrubbing one's hands against stainless steel mechanically removes the oils and grease responsible for the offensive food odors. The stainless steel doesn't actually do anything to neutralize the odors chemically, but the act of using it under running water helps to break up the surface tension on the skin. In theory, other materials such as plastic or rubber should perform the same action with similar odor-reducing results.
It is also possible that the chemical composition of the stainless steel, especially the chromium and chromium oxide, does interact with the sulfur compounds found in many odor-causing foods. The sulfur left on the cook's hands after handling onions or garlic could form a chemical bond with the chromium oxide on the stainless steel soap bar and cling to the bar's surface, not the cook's skin.
Because there is very little scientific evidence to support any of these claims, some experts suggest there is no real benefit to using a stainless steel soap bar. Ordinary soaps can remove many offensive chemical compounds if used immediately after food preparation, and latex gloves can be worn when working with odor-causing foods. Some cooks believe the stainless steel soap bar works better than traditional soap for more stubborn odors, but it is difficult to evaluate such claims without performing stringent "sniff tests" in a controlled laboratory environment.