MATERIAL ANALYSIS

One of the sgrafitto rondelles found on the west facade of each terrace. (UPenn 2002)

As part of the Scala d'Acqua condition survey, samples of mortar and stucco were prepared and analyzed under the supervision and aide of Ernesto Borrelli, Conservation Chemist, at ICCROM. The objective of the analysis was to identify the composition of the samples and better understand their original properties, appearance, and alteration over time. The identification of these components will guide future conservation efforts and digital reconstructions.

Five surface finish and mortar samples were taken from the west wall of the southern section of Landing Two:

• OB-SC-01 Stucco; rondelle sgraffito red background with white lower edge of the remaining sgraffito.

• OB-SC-02 Stucco; base layer, original north pilaster, west wall of south Landing Two.

• OB-SC-03 Stucco; finish layer,original and washes north pilaster, west wall of south Landing Two.

• OB-SC-04 Mortar; brick bedding mortar north pilaster, west wall of south Landing Two.

• OB-SC-05 Mortar West wall, south Landing Two.

The five samples were mounted in a Buehler Epoxide Resin composed of five parts resin to one part catalyst. The samples were cut into cross sections and analyzed under a Stereo Nikon PFX microscope. Images of these samples were taken with Zeiss Axiovision 2.0 software.

Both samples OB-SC-02 (scratch coat) and OB-SC-04 (brick bedding mortar) have similar compositions of evenly distributed puzzolana and lime. Similarly, samples OB-SC-03 (finish coat) and OB-SC-05 (mortar) have uneven distributions of small and large puzzolana within the lime binder. Sample OB-SC-01 is uncharacteristically poorly mixed for a finish coat consistent with sgraffito. All five samples were also prepared in thin section that will enable further study.

Images of the 5 mortar and stucco samples taken for laboratoy testing. (UPenn 2002)

To see the complete description of the material analysis and sample location key, go to downloads