Improved Sol-Gel Consolidants for Stone (2002-24)

The purpose of this project was to develop improved consolidants for restoration of stone damaged by weathering. Conventional consolidants are organic polymers or silica gels, which are simple materials that do not permit matching of a range of properties of the stone.

To provide consolidants with a wider range of properties, we prepared composite materials consisting of colloidal oxide particles suspended in a silicate matrix. Initially, we succeeded in preparing satisfactory suspensions by adsorbing a layer of nanosilica (silica particles with a diameter of 1020 nm) onto titania pigment particles. The silica layer prevents the titania particles from agglomerating, allowing them to penetrate deeply into the stone.

Later improvement of the suspension procedure resulted in consolidants that are much more stable and fluid. Stone treated with the particle-modified consolidant (PMC) increases dramatically in stiffness and strength. Most impressively in a sodium sulfate test, the PMC provided better protection than a commercial silicate consolidant.

The results of this research were reported at the Fall Meeting of the Materials Research Society in a symposium entitled, Materials Issues in Art & Archaeology VI. Continuing research is directed toward use of other colloidal particles, which will permit preparation of consolidants with a wider range of colors and properties.