Mechanical cleaning under magnification, image courtesy of Jessica Byler
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French Guiana Metal
Date: 1802-1860 Origin: Habitation la Caroline and Habitation Grand-Marée, French Guiana Dimensions (cm): key: 7 L, coins/button: 2 D Materials: copper alloy Institution: Musée des Cultures Guyanaises Key Treatment Steps
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Summary
This group of metal objects was treated in partnership with Elizabeth Clay, University of Pennsylvania Anthropology graduate student. The objects were excavated by Clay in the summer of 2016 and loaned to the Penn Museum for study and conservation. The group includes four metal objects: key and button, and two coins. Objects come from two different sites, Habitation la Caroline and Habitation Grand-Marée (GM), both located in French Guiana on the northeastern coast of South America. Sites are in the district of Roura, and the secondary rainforest area falls within equatorial and tropical monsoon climate zones. The excavations focused on former slave quarters of each plantation site, which were occupied during the second period of slavery in French Guiana.
Condition
Objects are stable and mostly complete with minor signs of corrosion and moderate surface dirt.
Treatment
Treatment aimed to provide analytical support and clarify object surfaces.
Imaging and analysis were completed prior to object treatment steps. The four metal objects were analyzed by portable X-ray fluorescence (pXRF) to characterize alloy composition. Variations on a copper and iron alloy were observed. See analysis section for further details. X-radiography was used to examine structural features and look for evidence of surface decoration. X-radiographs revealed low-relief surface decoration on the button and both coins, including imagery and lettering. Additionally, A Keyence 3D microscope was used to explore surface details and manipulate visibility in raking light. Examining surface details helped inform the cleaning process.
Mechanical cleaning proceeded based on the surface details observed through imaging techniques. Dirt and powdery corrosion were loosened and reduced to reveal intact surfaces.
Each object had slightly different patterns of corrosion product. Due to the presence of powdery, pale green corrosion product, the key was further treated with the application of a corrosion inhibitor followed by a coating. The key was submerged in 3% benzotriazole (BTA) in ethanol under normal atmospheric conditions.
After cleaning, coin and button surfaces were revisited with the Keyence 3D microscope to capture details revealed during cleaning. Details of illegible lettering were also captured to facilitate further study.
A protective housing was made to accommodate the four objects so that they could be easily viewed during study and eventually travel safely back to French Guiana.
This group of metal objects was treated in partnership with Elizabeth Clay, University of Pennsylvania Anthropology graduate student. The objects were excavated by Clay in the summer of 2016 and loaned to the Penn Museum for study and conservation. The group includes four metal objects: key and button, and two coins. Objects come from two different sites, Habitation la Caroline and Habitation Grand-Marée (GM), both located in French Guiana on the northeastern coast of South America. Sites are in the district of Roura, and the secondary rainforest area falls within equatorial and tropical monsoon climate zones. The excavations focused on former slave quarters of each plantation site, which were occupied during the second period of slavery in French Guiana.
Condition
Objects are stable and mostly complete with minor signs of corrosion and moderate surface dirt.
Treatment
Treatment aimed to provide analytical support and clarify object surfaces.
Imaging and analysis were completed prior to object treatment steps. The four metal objects were analyzed by portable X-ray fluorescence (pXRF) to characterize alloy composition. Variations on a copper and iron alloy were observed. See analysis section for further details. X-radiography was used to examine structural features and look for evidence of surface decoration. X-radiographs revealed low-relief surface decoration on the button and both coins, including imagery and lettering. Additionally, A Keyence 3D microscope was used to explore surface details and manipulate visibility in raking light. Examining surface details helped inform the cleaning process.
Mechanical cleaning proceeded based on the surface details observed through imaging techniques. Dirt and powdery corrosion were loosened and reduced to reveal intact surfaces.
Each object had slightly different patterns of corrosion product. Due to the presence of powdery, pale green corrosion product, the key was further treated with the application of a corrosion inhibitor followed by a coating. The key was submerged in 3% benzotriazole (BTA) in ethanol under normal atmospheric conditions.
After cleaning, coin and button surfaces were revisited with the Keyence 3D microscope to capture details revealed during cleaning. Details of illegible lettering were also captured to facilitate further study.
A protective housing was made to accommodate the four objects so that they could be easily viewed during study and eventually travel safely back to French Guiana.
Treatment Images
During Treatment and Analysis
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