Lots of good suggestions have been offered for the exposed limestone. A major reference, however, has not been mentioned. John Ashurst and Francis G. Dimes' book, Conservation of Building and Decorative Stone, Butterworth-Heinemann, should be on the bookshelf of any archaeologist doing work with architectural stone. Best, Michael Trinkley, Ph.D. Director Chicora Foundation, Inc. PO Box 8664 Columbia, SC 29202-8664 803/787-6910 Email: [log in to unmask]