Laundry stain removers chemically dissolve, emulsify or digest particles in fabric according to the organic properties that they posses. Common household stain removers fall into three general categories: solvents, enzymes and surfactants. Solvents dissolve stains, enzymes digest stains and surfactants emulsify, hide or lift stains from fabric.
Laundry solvents remove stains by using water-based or oil-based chemicals. Water-based stains may be removed by soap or club soda whereas oil-based stains may be removed by alcohol or gasoline based solvents. The type of solvent needed for stain removal depends upon the base of the stain.
Enzymatic removers digest proteins and fats in stains and most effectively remove food and blood stains. Popular oxygen-based removers use enzymes to break stains apart. According to experts at About.com, oxidizers like bleach, borax and peroxide can effectively lift or hide a stain.
Surfactants coat stains with emulsifying ingredients that soften material, making stain removal easier. Surfactants magnetize individual molecules. One side of the molecule adheres to the stain, and the other side of the surfactant molecules adheres to water molecules. During the agitation process, surfactants pull stain molecules apart, allowing them to remain affixed to the water molecules and to be effectively rinsed away from fabric.