For Stone Restoration, maintenance and supplies write to: stellab@bellsouth.net TIP OF THE MONTH: Acid to avoid on marble surfaces. Acid name: Hydrochloric acid, acetic acid, sulfmaci acid, phosphoric acid,oxalci acid, hydrofluoric acid, nitric acid. Marble is very sensitive to acidic chemicals. Some shampoos, for example, are acidic, and will leave a dull spot on marble. It is extremely important to keep any marble surface out of contact with acidic ingredients.