Once the surface is dull and rough, it gets dirtier and stains deeper, and you have to continue using a harsh abrasive to remove imbedded dirt and stain. Coarse abrasives can damage plastic, glass, nonstick surfaces on cookware, painted woodwork, and plated and highly polished metals. Menu Acids Acids are beneficial in removing hard-water deposits, discoloration from aluminum, brass, bronze, and copper and iron rust stains. Strong acids also eat away clothing, leather, skin and some metals. They can also irritate and injure the skin and eyes.
Vinegar removes hard-water deposits from glassware.
Lemon juice is a citric acid and works in much the same way as does vinegar. It is sometimes found in toilet bowl cleaners. Hydrochloric and sulfuric acid are used in dilute concentrations in some toilet bowl cleaners. Menu Alkalies Alkalies are soluble salts that are effective in removing dirt without excessive rubbing. They are good grease removers because the alkalies form an emulsion, a mixture where oily or solid particles are held in suspension.