Field studies generally consist of evaluating appearance and color changes in the field on field test stones and whole headstones. Additional laboratory analyses of field test stones are described in Section 4.3, Methods of Analysis.
5.2.1. Field Stone Samples
Figure 14. NCA staff members Genaro Ocrato and Pat Meyer help set sample stones at San Francisco National Cemetery.
Early in the summer of 2005, 6îx 6î x 24î marble slabs of Colorado Yule and Cherokee White marble were procured from two National Cemetery Administration contracted quarries. These stones would serve NCPTT as the needed field sample stones. Each of the five project cemeteries and the NCPTT labs were shipped a pallet of 22 stones in early June 2005. Of the 22 stones 11 were Colorado Yule and the remaining 11 were Georgia marble. In June, Church visited each of the cemeteries as an initial contact visit. During this visit the sample stones were paired with existing grave markers of the same marble type. Each of the sample stones was set approximately 6î in the ground for stability, see Figure 14.
During the fall trip to each cemetery, ten of the stones were taped into a grid and treated with each of the five cleaners plus water. Of the ten stones half were Colorado and half were Georgia marble. This same process was repeated in the spring on the remaining sample stones, leaving one of each type untouched as a control sample. In the fall of 2006, each of the stones were removed from the various cemeteries, cling wrapped and stacked on pallets. The pallets have recently been shipped to the laboratories and were received at NCPTT on April 2. They are awaiting testing. The tests preformed on the sample stones will be conducted to look for any physical or chemical changes to the marble itself or to identify any harmful residues left behind by the cleaners that may be harmful over time.