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Saturday, May 31 • 11:00am - 11:30am
(Research and Technical Studies Session) X-ray Micro Tomography Analysis of Western Red Cedar Secondary Phloem

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The secondary phloem of the Western red cedar (Thuja plicata) is used by Native American and Canadian First Nation communities of the Pacific Northwest coast in the production of cultural material. Analysis of Western red cedar secondary phloem tissue identified bio-mineral distribution patterns and variations in the structure of inner and outer tissue which may contribute to condition issues encountered in historical cultural material. X-ray micro-tomography of secondary phloem tissue identified known mechanisms of deterioration not readily visible with other examination techniques including cleavage of phloem layers along linear, tangentially arranged parenchyma and sieve cell tissue, and disruption of parenchyma and surrounding cells in semi-functional middle tissue and non-functional outer tissue. The data also indicated the presence of a relatively dense material distributed throughout phloem ray parenchyma and intercellular spaces, and concentrated in areas of cell disruption. In an effort to further characterize this dense material, transverse sections of phloem samples were analyzed with SEM-EDS; spectral peaks for calcium, likely indicative of calcium oxalate crystals were identified in these areas. These data suggest a link between bio-mineralization and abscission mechanisms in Western Red cedar phloem tissue, which may play a role in the shedding and tissue deterioration typically associated with movement and manipulation of historical material.

Speaker(s)
PM

Peter Mc Elhinney

Conservation Fellow, Smithsonian Institute
Peter Mc Elhinney is the current Postgraduate Fellow in Conservation of Museum Collections at the Smithsonian Institutes National Air and Space Museum. Peter studied Conservation of Organic Materials at Camberwell College, University of the Arts, London, before working as a conservation volunteer at the British Museums Department of Organic Artifact Conservation, and completing a two year Postgraduate Andrew W. Mellon Foundation Fellowship in... Read More →

Co-Author(s)
BA

Benjamin Ache

Production Manager, Micro Photonics, Inc.
avatar for Nicole Little

Nicole Little

Physical Scientist, Smithsonian Museum Conservation Institute
Nicole Little is a Physical Scientist at the Smithsonian Institution’s Museum Conservation Institute. She received both her B.A. and M.A. in Anthropology from the University of Missouri-Columbia, where her master’s research dealt with the compositional analysis of Mayan ceramics from northwest Belize. Her areas of interest include the quantification of heavy metals in bone by inductively coupled plasma-mass spectrometry and the... Read More →


Saturday May 31, 2014 11:00am - 11:30am
Seacliff A-B

Attendees (14)