CRACKING OF ORGANOSILICONE STONE CONSOLIDANTS IN GEL FORM

It has been suggested that there may be some risk from the repeated application of organosilicone consolidants on stone which has been previously treated with these consolidants: gels generated by the polymerization of mixtures containing an organometallic catalyst are unstable and may crack. The present paper assesses the effects of the quantity and type of catalyst on the stability of the resulting silica gel when it comes into contact with selected liquids. The behaviour of gels prepared from commercially available stone consolidants is also studied. According to these experiments it can be concluded that gel stability is related to the amount and type of catalyst. Gels prepared by alkoxysilane poly condensation with acid catalyst are more stable than those prepared by poly condensation with dibutyltindilaurate (DBTDL) as catalyst.