The New York Public Library: Protective Treatment for Sugaring Marble

Abstract

The marble of the New York Public Library was found to be in a fairly good state of conservation except for the more exposed elements, such as quoins and the many delicately carved elements that decorate the building. This paper focuses on the treatment developed for areas that showed significant sugaring. For this purpose, laboratory examinations and analyses were carried out and preliminary tests were made with silicate ester-based consolidants. These, however, did not perform well in test studies and therefore an approach using inorganic materials was developed. The treatment consisted of spray application of an ammonium oxalate solution that reduced the intensive sugaring of the marble. To further protect these eroded surfaces, a shelter coat based on Type S hydrated dolomitic lime was also applied. This method is fully compatible with the marble substrate and follows the overriding principle of minimum intervention, as stated by the Venice Charter.