During August 2014, Senior Lecturer and Conservation Scientist Fran Gale conducted a National Park Service workshop on the examination of historic mortar materials. This two and one-half day workshop was hosted by the National Center for Preservation Technology and Training, a research and development center for the National Park Service located in Natchitoches, Louisiana. http://ncptt.nps.gov/
Workshop participants included conservation scientists and conservators from the National Center for Preservation Technology and Training, NPS staff from Cane River Creole National Historical Park and San Antonio Missions National Historical Park; faculty members from UT San Antonio College of Architecture and historic preservation specialists from the Mississippi Department of Archives and History. SOA graduate student Izabella Dennis assisted with the workshop.
The workshop included classroom lectures on mortar components; curing mechanisms for lime, Natural cement and Portland cement mortars; deterioration processes; and the materials and procedures used to replace damaged and missing original mortars. The workshop also included hands-on laboratory sessions where participants examined samples of historic mortars, plasters and stuccoes and conducted tests to determine the materials and mix designs.
Site visits to historic plantations in Natchitoches Parish provided an opportunity for workshop participants to inspect historic structures with original and replacement mortars. A tour of Magnolia Plantation, an early 18th century site that is now part of Cane River Creole National Historical Park, focused on the surviving brick quarters which originally housed slaves, and then sharecroppers following the Civil War. http://www.nps.gov/cari/historyculture/magnolia-plantation-history.htm At nearby Melrose Plantation, a National Historic Landmark, workshop participants examined original materials of African House, an early 19th brick building. Bousillage, a plaster-like material composed of red dirt, dried Spanish moss and deer hair, is exposed on one of the interior walls of African House. http://www.melroseplantation.org/
The final workshop session included an introduction to instrumental methods such as x-ray diffraction, petrography and scanning electron microscopy that are used to further analyze historic mortar materials. The workshop concluded with a discussion of test data obtained during the obtained during the laboratory sessions and how the information is used to develop recommendations for restoration work.