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Newswise SciNews – 2/8/07 - Archaeologists are now turning to
forensic crime lab techniques to hunt for dyes, paint, and other decoration in
prehistoric textiles. Although ancient fabrics can offer
clues about prehistoric cultures, often their colors are faded, patterns dissolved,
and fibers crumbling. Forensic photography can be used as an inexpensive and
non-destructive tool to analyze these artifacts more efficiently, according to
new Forensic photography helps
researchers collect information from fragile artifacts before using expensive
chemical tests, which cause damage during material sampling. The forensic
method also helps researchers narrow areas to sample for colorants, ultimately
reducing artifact damage and testing costs. "Normally when you dig
artifacts out of the ground, especially stone or ceramic ones, you wash them
and they look sexy. But you can't do that with textiles," said Christel
Baldia, Putting forensic photography to the
test, Baldia and Jakes examined textiles from burial mounds built by the "Textiles often come out
looking like brown rags, yet Native American dress is described as colorful by
early travelers or pioneers." Baldia said. "So we asked ourselves:
'What can we do to better examine ancient textiles for colors we no longer
see?'" Forensic scientists use different
light sources, such as ultraviolet and infrared, to visualize stains or
fingerprints on clothing, but Jakes said no one has used those methods in
looking at ancient textiles. "In a way, it's like shopping for
clothes," she said. "You need to see the clothing in different
lighting-a fabric looks like it matches in the store's lighting, but when you
bring it into sunlight the colors change." Under non-visible light, many
pigments and dyes absorb light energy but release it in different wavelengths,
or colors, of light. This behavior is called fluorescence, and it can reveal
faded or deteriorated artwork in textiles. Fluorescence normally helps forensic
investigators find blood stains, fingerprints, body oils, and other evidence
where there appears to be none (such stains can be visible even after washing
thoroughly). To find fluorescent patterns in
textiles, Baldia and Jakes simulated daylight, ultraviolet light (between 254
nm and 365 nm), and infrared light (between 800 nm and 900 nm), then
photographed the artifacts with special film and light-filtering camera
equipment. The photographs ultimately helped them see undetected patterns and
markings in some of the artifacts they examined. "The materials we examined from
When archaeologists are curious
about an ancient fabric's colors, they often sample the material at random and
cause damage to it. Photographing artifacts with Baldia and Jakes' method
before sampling, however, helps archaeologists build a focused game plan for
sampling that minimizes harm to the material. "The code of ethics from the
American Institute of Conservation is 'do no harm'," Jakes said. "For
the artifact to stick around for as long possible, you have to be as minimally
destructive in your sampling as possible." Baldia said sampling ancient fabric
always requires removing a fiber or piece of yarn. "People essentially do
this randomly, but forensic photography helps minimize damage by enabling us to
sample strategically," Baldia said. If archaeologists see a
pattern in forensic photographs, she said, then the area most likely contains
dye or paint-and focusing on such areas ultimately provides more information
about ancient civilizations while cutting research costs. Baldia explained that she and Jakes
got the idea to photographically analyze textiles from museum painting
conservators. "Art museums use it to see if a
painting has been painted over, if it's a forgery, and so on," Baldia
said. "We thought: 'why aren't we doing this with ancient textiles?' Just like
other art, fabrics are dyed and painted, and this is an inexpensive way to
gather important information." The researchers hope their technique
will become standard practice for analyzing textiles and even other organic
artifacts, like wood or leather. "I think this will help spur a
lot of new findings," Jakes said. "It's a great way to start looking
at the stuff in the attics of museums across the country in a new way." Funding for the project was granted
by the -- |