Improved Impregnation Technique for the Preservation of Stone Statuary

ATMOSPHERIC attack on stone statuary has increased considerably during the past few decades because of the presence of increasing amounts of gaseous pollutants such as SO 2 and CO 2 (ref. 1). There are two types of technique 2 for the preservation of stone: those which provide, by means of impregnation, both a protective coating and a cement between dislodged grains; and those which change the chemistry of the stone so that the resultant substance is more resistant to attack.