Stain and deposit removers are substances designed to remove spots, usually with the aid of abrasive materials such as steel wools and brushes. They are typically commercialized in fluids and stick forms, but they can also be sold in powder and paste forms. These substances contain crystalline and amorphous silica, feldspar, clay, and chalk alongside surfactants, solvents, and enzymes. They are sometimes improved by adding ingredients such as sodium carbonate, bleaching agents, and oxalic acid.