Barium hydroxide as stone consolidant: preliminary results on Gioia Marble

Although barium hydroxide has been frequently used in recent years for the consolidation of frescoes and wall paintings, very few studies have been undertaken about its use in treatments of stone monuments and objects. Since it is widely believed that because of their greater similarity to the composition of the substrate, inorganic products should give better results in the conservation of stone materials than organic substances, the objective of this study is the evaluation of a possible application of barium hydroxide as a stone consolidant. The product was applied to Gioia marble samples. The specimens were treated with two different procedures: by immersing the stones in the water solution, and by applying poultices as supportant of the solution to the samples' surfaces. Different soaking times were tested for the immersion treatment: for the poultice treatments, different concentrations and contact times were used in order to identify the best application procedure. The properties of the stone were verified before and after the treatments by measuring water absorption, color variations and drilling force. Studies were also conducted on the mechanism of barium hydroxide carbonation.