Reducing Marble SO sub(2) Reaction Rate by the Application of Certain Surfactants

Rectangular slabs of Carrara marble were used to evaluate the use of selected surfactants to reduce the effects of atmospheric sulfur dioxide on marble. The samples were either untreated or treated with solutions of dipotassium monohydrogen phosphate, potassium oxalate, sodium fluoride, or sodium oleate at different concentrations. All four treatments led to the formation of new chemical compounds at the stone surface due to the reduction of respective anions from their solutions. The samples treated with sodium oleate adsorbed less water vapor than the untreated samples, but treatments with oxalate, fluoride, and phosphate caused increased moisture adsorption compared to untreated controls. Subsequent exposure of marbles treated with either potassium oxalate or sodium oleate to SO sub(2) atmosphere in a rain-sheltered area resulted in significantly more protection from attack. However, the protection was reduced significantly when exposed to rain over an extended period.