Presentation on theme: "XRF Applications on Native American Collections Cheryl Podsiki The Field Museum, Chicago Symposium School for Advanced Research Indian Arts Research Center,"— Presentation transcript:
XRF Applications on Native American Collections Cheryl Podsiki The Field Museum, Chicago Symposium School for Advanced Research Indian Arts Research Center, Santa Fe, NM May 28, 2009
Applications Manufactured for use in Environment : Soil samples Modern Metal Alloys : Scrap metal industry Analytical Standards Adapted for use by Health Department : Lead paint, asbestos, plastics, electronics, toys, pesticides Museum Collections and Research : Metal alloys, glass, ceramics, obsidian, minerals, pigments, paints, mordents, textiles, paper, leather, hide, skin, fur, felt, feathers, shell, bone, ivory, plastic, minerals, geological specimens, taxidermy specimens, pesticides
Conservation Use in Collections Bruker-AXS Tracer III-V analyzer, Rhodium source Analysis of unknown residue Pesticide Check Pigment identification Glass: Lead
Archaeological Field Work Innov-X Alpha Series, Tungston source Portable XRF for floor chemistry Lab set-up for obsidian
Archaeological Metals Wari Tupu AD 600-1000 LA-ICP-MS : Cu 97.50 and As 1.98% Hopewell Antler Headdress: Native Copper; Reconstructed for WCE, 1893, using iron based metal rods, plaster, pigments, adhesive; Subsequent conservation repairs used wood dowels, more pigments, different adhesives. Lead top to condiment bottle; early 20 th century. XRF
Confirmation of Lead Glass Eyes Buddha face gesso / wood (red) over glass eye (blue). 33 kV; 2.20 µA; Titanium- Aluminum filter; no vacuum; 60 seconds.
Archaeological glass, Glass Beads, Ceramics, Obsidian, Chert Glass beads from Kenya analyzed with LA-ICP-MS; XRF Cadmium, Zinc, Arsenic, Lead Cadmium, Zinc Lead, Arsenic
Testing Process: options, flexibility Short Pre-test Visit by Tribal Representatives to Museum Cultural handling, restrictions, issues, concerns Tribal reason (s) for test: use, retire, storage Basic methodology for using XRF Documentation requested by Tribe and by Museum Longer Visit for purpose of conducting XRF analysis together *Discuss issues connected to XRF analysis Better idea of sample sites and documentation needed Museum staff completes testing and final documentation Visit by museum staff to tribal community to present and discuss results/demonstrate XRF analyzer.
Mapping and Results Documentation 1 2 8 3 4 5 6 7 9 10 11 12 Sample siteArsenic (As)* Bromine (Br) Lead (Pb) Mercury (Hg) 1 broken blue beads xndx 2 red beadsxndx 3 yellow beadsnd x 4 dark blue beadsnd x 5 sky blue beadsxndx 6 pink beadsxndx 7 green beadsnd x 8 buckskin toe, top nd x 9 buckskin toe, bottom nd x 10 red fabric lining xndxpossible 11 buckskin heel, back nd x 12 Tyvek insert support nd Test date: 2/10/2007 Instrument operator/handlers: Cheryl Podsiki Instrument: Bruker-AXS Tracer III-V analyzer Voltage (kV): 40 Current (μA): 8 Filter: Copper-Titanium- Aluminum Vacuum: No Acquisition time: 60 seconds Test Notes: The broken blue beads contain lead and arsenic, but the buckskin toe # 8 showed only a comparative trace of lead (likely from cross-contamination of bead residue) and no arsenic. Readings taken from the toe, heel, and bottom of the buckskin showed the same results. The presence of arsenic is likely from glass composition and not from pesticide. The Tyvek support was checked for cross-contamination purposes.
Pesticide or Inherent? The blue beads are deteriorating due to glass disease. Glass residue is present in the housing container and on the bottom surface of the moccasin.
Spectra overlay of Buckskin and Beads The broken blue beads (blue spectrum) contain lead and arsenic. The top of the buckskin toe (red spectrum) exhibits very little lead and no arsenic. It is likely that the presence of lead and arsenic is due to glass manufacture and not pesticide.
Cinnabar/Vermilion Rare red Chinese paper rubbings, Laufer collection, 1900-1910. Vermilion Red Lead Realgar (mercury) (arsenic) Pigments on Objects
Blue spectrum is the red pigment; red spectrum is the bare wood. Lead Mercury Red pigments tested Blue spectrum is the red pigment; red spectrum is the bare wood.
Brown Feather. 40Kv; 8µA; Copper-Titanium-Aluminum filter; no vacuum; 180 seconds. Seed bead and feather necklace from South America Feathers
Wood Box Box exterior (red) over interior (blue). 40Kv; 8µA; Copper-Titanium-Aluminum filter; no vacuum; 60 seconds.
Red Pigmented Buckskin Pouch Exterior (red) over Interior (blue). 40Kv; 8µA; Copper-Titanium-Aluminum filter; no vacuum.
Exterior front center (red) over interior front center (blue). 40Kv; 8µA; Copper-Titanium-Aluminum filter; no vacuum; 60 seconds. Spot test for arsenic was positive. Buckskin Ceremonial Item
Natural Pigments: Two Yellows Two yellow pigments: Sample 10, a calcium based pigment, (blue spectrum), exhibits a significant arsenic peak compared to Sample 11, a silicon based pigment (red spectrum), which exhibits a much lower arsenic peak.
Natural Pink Pigment The silicon and iron based pink pigment exhibits a fairly significant arsenic peak. Results of laser-ablation (LA-ICP-MS) analysis show 698 ppm arsenic in this sample.
Issues encountered Museum Field Museum has massive collections with wide range of materials but resources are lacking for further research/experimentation: funding, staff, department priorities – same problem as in other non-university museums and smaller institutions Isolation of issues unless network with other users Practice and experience is a must for interpretation; lack of resources for support. XRF Spectral interference Interpretation: subjective; two people needed Need “standard” reference materials to provide semi-quantitative results Results: even semi-quantitative or quantitative results cannot answer the ultimate question: “What does it mean?” Must get medical community involved.
Cultural representatives – cultural, spiritual, legal Conservator/collections manager – past and present museum procedures and object history; material characterization; conducts test; interprets results Analytical chemist or physicist – primary or secondary interpretation of results; conducts test Medical / health professional such as a toxicologist, industrial/occupational hygienist – safe handling guidelines; health effects Manufacturer scientist of specific instrument – shares pertinent information about instrument and known applications; R & D to continue development of needed technology for museum application Wider circle of XRF users/institutions – network; share information; research; beginners, previous users and experts Team approach
“The issues are complex and resources too little – an information network among XRF users and institutions is vital to finding solutions.” Participants, 2008 XRF Seminar at The Field Museum