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XRF Applications on
Native American CollectionsCheryl 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 20th 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
Cadmium, Zinc
Lead, Arsenic
Lead, Arsenic
Heavy Metal Pesticide Residues
Detected • Arsenic compounds [inorganic]• Lead or lead compounds [inorganic]• Mercury compounds [likely inorganic, possibly
organic]• Zinc compounds [inorganic]
• Ethylene bromide (bromine residue remains) • Ethylene dibromide [fumigant] (bromine residue
remains) • methyl bromide (bromine residue remains) • Methylene bromide [halogenated hydrocarbon]
(bromine residue remains)
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
34
5
67
9
10
1112
Sample site Arsenic(As)*
Bromine(Br)
Lead (Pb)
Mercury (Hg)
1 broken blue beads
x nd x nd
2 red beads x nd x nd
3 yellow beads nd nd x nd
4 dark blue beads nd nd x nd
5 sky blue beads x nd x nd
6 pink beads x nd x nd
7 green beads nd nd x nd
8 buckskin toe, top
nd nd x nd
9 buckskin toe, bottom
nd nd x nd
10 red fabric lining
x nd x possible
11 buckskin heel, back
nd nd x nd
12 Tyvek insert support
nd nd nd nd
Test date: 2/10/2007 Instrument operator/handlers: Cheryl PodsikiInstrument: Bruker-AXS Tracer III-V analyzer Voltage (kV): 40 Current (μA): 8 Filter: Copper-Titanium- Aluminum Vacuum: No Acquisition time: 60 secondsTest 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