3.7 The Use of Epoxy Resins for Stone Consolidation
 

The Getty Conservation Institute

Charles Selwitz
Period of Activity: 1989-1991

Project Abstract
A technical report for the Research in Conservation series has been written that deals with the use of epoxy resins for stone consolidation.

Major Findings
Epoxy resins are favored polymeric adhesives for stone. They impart much higher mechanical strength to porous rock when used as a consolidant than do silanes or acrylic polymers. Nevertheless epoxy resins have not been widely used to strengthen fragile substrates. A study of the conservation literature discloses a conventional list of concerns such as the lack of reversibility, color, viscosity, etc., but the real reason appears to be that effective methods of application are not well established. Most studies in conservation make application of the resin to the test stone in the most direct manner with poor to mixed results. Only Wieslaw Domaslowski of the University of Torun, Poland, has done formulation research in depth and has successfully treated and monitored portions of a number of buildings. His primary references are in Polish and are not readily available. This project is concerned with the analysis of the literature on the use of epoxy resins for stone preservation and involves translation of the Domaslowski papers we can obtain. It includes research and documentation of the limited number of buildings treated with epoxies, including both failures, and successes.

Primary Publications:

Selwitz, C., "The Use of Epoxy Resins in Stone Conservation," Materials Issues in Art and Archaeology II, Vol. 185, 1991, Proceedings of the Materials Research Society, Spring Meeting, San Francisco, California, April 16-20, 1990, pp. 181-191.

ABSTRACT-An overview on the causes and methods of treatment of stone deterioration is presented. The reasons for and prejudices against epoxy resins for stone consolidation are described in terms of achieving deep penetration, improvement in mechanical strength, and good water repellency without the inhibition of water vapor transmission. Early work that failed to understand the nature of epoxy curing in solution is outlined, and more recent research, where this problem has been solved, is discussed.

Selwitz, C., Epoxy Resins in Stone Conservation, Research in Conservation, Nš 7, The Getty Conservation Institute, 1992.

ABSTRACT-See project abstract.

Ginell, W.S., R. Kumar, and E. Doehne, "Conservation Studies on Limestone from the Maya Site at Xunantunich, Belize," Materials Issues in Art and Archaeology IV, Vol. 352, 1995, Symposium held May 16-21, 1994, Cancun, Mexico, Materials Research Society, Pittsburgh, Pennsylvania, pp. 813-821.

ABSTRACT - The limestone used in the construction of much of the 8-11th century Maya structures at Xunantunich, Belize is mechanically weak. Active microfloral growth, cyclic changes in humidity and temperature, and exposure to the erosive effects of wind and rain have resulted in deterioration of the stone used at the site. Limestone samples were consolidated using water-compatible and other consolidants and were exposed to both sunny and shaded tropical environments for one year. Data-logging meteorological stations were use to monitor the temperature, relative humidity, rainfall, wind conditions and solar irradiance during the exposures. Accelerated aging tests on similarly treated specimens were performed in the laboratory. Dilute epoxy and acrylic resin systems in hydrophilic solvents were found to penetrate and consolidant weak limestone. Several biocides applied in dilute aqueous solution were effective in preventing microfloral growth on new limestone and for controlling in situ growth on historic limestone.

Ginell, W. S., P. Kotlik, C. M. Selwitz, and G. Wheeler, "Recent Development in the Use of Epoxy Resins for Stone Consolidation," Materials Issues in Art and Archaeology IV, Vol. 352, 1995, Symposium held May 16-21, 1994, Cancun, Mexico, Materials Research Society, Pittsburgh, Pennsylvania, pp. 813-821.

ABSTRACT - Amine groups in epoxy resin curing agents may be responsible for the effectiveness of this consolidant in limestone. Changes in stone appearance caused by the use of epoxy consolidants can be minimized by proper resin selection, application procedures and by modest outdoor exposure. Vacuum impregnation of deteriorated stone with epoxy resins results in deep penetration and is a process now in commercial use.