Household bleach is the chemical sodium hypochlorite. In addition to being used for cleaning laundry, it is used extensively in industry as a sanitizing agent. The following information is from a Proctor & Gamble website (http://www.scienceinthebox.com/en_UK/glossary/bleaches_en.html). Further information can be found on Wikipedia under “sodium hypochlorite” (http://en.wikipedia.org/wiki/Sodium_hypochlorite). ---------------------------------------- Bleach helps the cleaning process by removing and / or decolourizing stains (i.e., whiten or lighten colors). The key mechanism is a chemical reaction that "cuts" the stain molecules in smaller pieces that are more easily removed. Bleach can also acts by removing their color so that the stains become invisible. These processes may all work simultaneously on any given organic stain. The first mechanism of bleach action is quite similar to what enzymes do: the larger stain molecules are broken down into smaller, more water-soluble fragments, which are more easily removed by mechanical action or through the action of other detergent ingredients. Unlike enzymes, however, the action mechanism of bleach is a self-destructive one: the bleaching agents disappear in the course of the wash cycle. The action of bleach complements that of the surfactants and enzymes in the wash. Some soils that surfactants and enzymes may leave behind, or may only partially remove, are removed by bleach. Also, the fragmenting action of bleach makes the job of surfactants and enzymes during the wash easier. Bleach is an active molecule that can chemically reacts with different type of substrates. There are many different kinds of bleaches. When the substrate is a stain, the action of bleach is desirable. When the substrate is a dye in a fabric, the action is not desirable. Chemically speaking, the mechanism of bleaching may be oxidative or reductive; in laundry and cleaning products, oxidative bleaches are used. Oxidative beaches are compounds that release hydrogen peroxide (H2O2) or singlet oxygen during the wash, or they may be peroxides of organic acids also known as peracids themselves. Hypochlorite, peroxides, peracids, singlet oxygen are very reactive chemical species; they react with certain parts of organic matter that are responsible for its color. As a result, the organic matter becomes colorless; hypochlorite/peroxide/peracid/singlet oxygen are used up in the process. Some of the reactions between bleach and organic matter result in the actual breakage of bonds in the organic matter, thereby releasing smaller molecules of organic matter that are more water soluble. Hypochlorite, hydrogen peroxide (H2O2), singlet oxygen and peracid are the actual, oxidative and so-called bleach actives. They act directly on the stains. The different types of bleaching system have different stain removal/ fabric/color care profile. Formulators choose them based on the benefits they want to achieve.