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Ancient Egyptian pigment provides modern forensics with new coat of paint

Ancient Egyptian pigment provides modern forensics with new coat of paint

It was during a trip to Indianapolis that Professor Simon Lewis, a forensic and analytical chemist, was approached by Gregory Smith from the Indianapolis Museum of Art (IMA) with an idea.

Smith, senior conservation scientist at the IMA, had read and known of Lewis' search for new luminescent compounds that could be used in fingerprint detection.

It was common practise in Smith’s work to use white light to sweep ancient painted artefacts to find traces of an ancient pigment, which was revealed by viewing in the near infrared part of the spectrum.

Egyptian Blue is considered to be the earliest known artificial pigment with origins dating back to 3200 BCE. Even on artefacts dating back several thousands of years, Egyptian Blue still glowed brightly in the near infrared.

Smith asked if Lewis had considered using artistic pigments in his fingerprint research?

The rest as they say, was history.

Egyptian Blue pigment was found to be a promising candidate as luminescent fingerprint dusting powder . Under visible light it lit up the fingerprints in the near infrared against non-porous or patterned surfaces, such as polymer notes or soft drink cans, outperforming commercially available fingerprint dusting powders.

The findings could bring new colour not only to the field of modern forensics but also challenges in artefact conservation, demonstrating how the past could provide solutions for the future.

Out of the blue

Egyptian Blue is a pigment with a remarkable lineage that showcased the ancient Egyptians' highly advanced grasp on chemistry.

The colour is a synthetic product, prepared with a mixture of copper-containing material, sand and a strong alkali . The compound is then roasted to around 800℃ to 900℃ under very tightly controlled conditions.

Ancient Egyptian mask image showing Egyptian blue pigment. Indianapolis Museum of Art, Author provided

In ancient Egypt, this vivid blue product was highly favoured and widely used as a pigment in paintings such as tombs and mummies' coffins.

The faience technique used a blue ceramic glaze that contained Egyptian Blue on art objects such as amulets and figurines.

  • Egyptian Blue – The Oldest Known Artificial Pigment
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Egyptian blue was widely used by ancient Egyptians as a ceramic glaze known as faience, shown in this hippopotamus figurine. Carole Raddato/Wikimedia Commons , CC BY-SA

Beyond its brilliant blue colour, the pigment also glowed in near infrared, a characteristic that researchers had their eye on.

“You can use that to detect latent fingermarks on non-porous surfaces,” Professor Simon Lewis , from the Nanochemistry Research Institute at Curtin University, told The Conversation.

Fingerprint detection is still a critically important part of forensic investigation. To detect a fingermark, a dusting powder is used that that would provide the highest possible contrast to the surface, in order to show the ridge and contour details of the fingerprint.

But in the case of highly patterned, dark or reflective surfaces, this can prove troublesome.

The advantage of Egyptian Blue is that when you shine white light on the pigment, it is able to absorb the energy from the light and then emit it in the near infrared part of the spectrum, which our eyes are unable to see.

Lewis said a similar example could be seen in a gin and tonic, but in the ultraviolet light spectrum.

“Have you ever held up a glass of gin and tonic and seen a blue haze in it?” he said.

“What you are seeing there is the quinine in the tonic water, which is a fluorescent compound. It absorbs the ultraviolet light and then emits it as visible light.”

Latent fingermarks dusted with micronised Egyptian blue. Ben Errington, Author provided

Researchers from Curtin University and conservation scientists from the Indianapolis Museum of Art showed that using Egyptian Blue as a dusting powder consistently provided good contrast compared to commercial powders, with it glowing brightly even on difficult surfaces.

The method of using white light to illuminate the fingerprints was safe, simple and inexpensive. A slightly modified digital camera was used to photograph them, by removing a filter that usually prevents near infrared light from getting to the camera sensor.

The hard grind

Fortunately for Lewis’s team, Egyptian Blue is still being manufactured. Its main users are art restorers and conservation scientists, who still favour using the traditional pigments.

“There are a lot of artists and of course conservation scientists who like to use the older pigments. It’s readily available and can be purchased relatively straightforwardly,” Lewis said.

But they couldn’t just use the powder as it manufactured. Lewis said the original pigment particles were far too large and not up to fingerprinting standards.

“We actually had to reduce the particle size so that it was small enough to stick to the fingerprint,” he said.

So they employed an instrument more commonly used to prepare rock samples for chemical analysis. This microniser was able to break down the particle size of the pigment through centrifugal force.

“There have been a few examples of people looking for near infrared emitters for fingerprint research over the last few years, but the beauty of this one is that it is the lovely intersection between art and science.”

A starting point

Lewis said the study is only a starting point and researchers need to go further to see whether Egyptian Blue can be improved for forensic use.

“We are looking at both heavy and light impressions and wider variety of surfaces,“ he said.

“We are also looking into seeing if we can look at the properties or modify them, coatings that allow them to stick better. There are still bags of work to be done.”

Ancient Egyptian Powder Makes Fingerprints Glow

Crime scene investigators are about to get an assist from the land of the pharaohs. New research has shown that a pigment called Egyptian blue, formulated some 5,250 years ago, can be used as dusting powder to detect fingerprints on complicated surfaces.

The earliest known synthetic pigment, Egyptian blue is found in some of the paint that still colors ancient statues, coffins, and tomb walls. Modern scientists were intrigued by this long-lasting tint and figured out its chemical components decades ago. More recently they discovered that it emits near-infrared radiation when exposed to a certain kind of light. Researchers have now demonstrated the forensic potential of that rare, invisible luminescence.

After a crime is committed, police may dust relevant surfaces with a powder of a contrasting color. The powder sticks to the unique features of any fingerprints, providing visual proof that an individual was there. But prints may be hard to pick out on a shiny or highly patterned surface. That’s where Egyptian blue can make a difference.

The pigment is brushed on as usual. But the surface is then photographed under a white light with a modified camera and a filter sensitive to near-infrared rays. If fingerprints exist, they glow clearly in the resulting image.

One company is already marketing the powder, says Australian forensic chemist Simon Lewis, a member of the research team. “We expect it won’t be long before it’s used by law enforcement.”

Ancient Egyptian pigment provides modern forensics with new coat of paint - History

In ancient times, the manner of death was naturally assumed by where and how the victim had been found. For example, a man found in a body of water would naturally have drowned, while a man found lying broken and bloodied along the side of a road would have naturally fallen and possibly been dragged by a horse.

Suspicion of motive and the word of others against a possible murderer took precedence over any other facts, and when all else failed, torture was readily available to procure a confession.

During the middle of the 12 th Century, ancient Chinese were credited with being the first to attempt to define the difference between natural death and criminal intent. In a book written by Sung Tz'u called The Washing Away of Wrong, the author observed that water collected in the lungs of drowning victims and that strangulation could be assumed by damaged cartilage in the neck. As he so wisely said, so many hundreds of years ago, "The difference of a hair is the difference of a thousand li." (A li is the word that designates the distance of a mile in the Chinese language). The book became an official text for coroners.

In 1775, Karl Scheele realized he could transform arsenious oxide into arsenious acid, which, when combined with zinc, produced arsine. This discovery led to the eventual ability to detect arsenic poisoning.

By the early 1800s, the recognition of fingerprint patterns was studied, but decades would pass before that observance was applied to criminal and personal identification.

In 1835, a former Bow Street Runner employed by Scotland Yard was the first documented case of law enforcement comparing bullets to catch their man. Henry Goddard noticed a flaw in a bullet that was traced back to the original bullet mold.

A few years later, a doctor "experimenting" with the corpses of dead soldiers in Malta discovered that body temperature dropped at regular intervals following death, and could be used to determine time of death.

The discovery that fingerprints were unique to each individual and could provide identification of a particular individual, urged the state of forensic crime investigation to the forefront in 1788 when Dr. Nathaniel Grew published an illustrated anatomy book in which he claimed that "the arrangement of skin ridges is never duplicated in two persons."

Decades later, William Herschel, a Briton working and living in British India, demanded that his contracts be "signed" with fingerprints so that it would be "impossible to deny or forge. The impression of a man's finger on paper cannot be denied by him" he stated. Naturally, he was scoffed at.

Across the miles, another Briton living in Japan had come to the same conclusion. Henry Faulds was curious whether or not fingerprints remained the same despite efforts made to erase such fingerprints. He experimented with volunteers, introducing pumice stone, sandpaper and even acids to determine if fingerprints would appear different after new skin growth. They didn't.

In a paper published in the 1880 scientific journal called Nature, Faulds wrote that bloody fingerprints or impressions on a variety of surfaces could be used for "the scientific identification of criminals." Today, this is known as dactylography.

A German scientist named Christian Schonbein, who observed that hemoglobin had the capacity to oxidize hydrogen peroxide, which caused it to foam, inadvertently discovered the first presumptive test for the presence of blood in 1863.

By 1879, another German, Rudolph Virchow, was one of the first to note the differences and unique characteristics of hair in the pursuit of individual identification.

In 1888, during the reign of England's most notorious serial killer, Jack the Ripper, the use of crime scene photographs were extensively studied in an effort to detect clues and criminal profiling of the vicious murderer. Scotland Yard is the first to have attempted criminal profiling as a result of the Ripper's savage modus operandi.

By the early 1900s, the field of forensic investigation achieved major developments, due to the design and use of modern forensic methods and discoveries such as Benzidine, a chemical compound used to develop a universal, presumptive test for blood.

Perhaps the most famous of forensic developments, at least on a psychological level, was the statement made by Edmond Locard, who stated that "every contact leaves a trace". The phrase, published in Locard's paper, L'enquete criminelle et les methods scientifique, in 1904, and which is also popularly known as Locard's Exchange Principle, remains the backbone of forensic science collection and recovery to this day.

By the beginning of the 19 th century, the study of hairs, fingerprints and blood thrust the development of forensic investigation to new heights. Locard, the forensic professor at the University of Lyons, France, created the first crime laboratory for use by police and other law enforcement personnel.

In 1924, the first American police crime lab was created in Los Angeles, California and the Sacco and Vanzetti case publicized the popularity of microscopic comparisons of bullets used in their case. Following the Valentine's Day Massacre in 1929, Calvin Goddard founded the Scientific Crime Detection Laboratory at the Northwestern University in Evanston, Illinois.

By 1930, an American Criminalist named Luke May had developed tool mark striation analysis and observations and published in the American Journal of Police Science an article discussing the importance of discerning identification and differences in knives, tools and other instruments.

Just prior to the Second World War, a German named Walter Specht developed a chemical reagent called luminal, still used to this day as a presumptive test for the presence of blood.

The years following the war exploded with developments, including techniques for lifting fingerprints using a tape-lifting method, voiceprint identification and perhaps the most famous discovery in the history of forensic science, the discovery of the unique structure of DNA by Watson and Crick in 1953.

By the mid 1960s, forensic developments led to the identification of firearm residues left on skin and clothing, Breathalyzer tests to determine sobriety and determinations of post-mortem cooling had been perfected.

By 1975, the U.S. Supreme Court disseminated the Federal Rules of Evidence, which were enacted by a congressional statute. These rules stated that scientific evidence must be deemed relevant and not prejudicial for presentation in any criminal case. A mere two years later, the FBI began to use computerized scans of fingerprint cards from thousands of individuals in their Automated Fingerprint Identification System, more commonly known by law enforcement personnel today as AFIS.

Advancements in research of DNA profiling and blood analysis perfected methods such as RFLP (restriction fragment length polymorphism) and PCR (polymerase chain reaction) testing made it possible to identify victims as well as suspects in a process commonly known as DNA Fingerprinting, the most famous of forensic discoveries of the 20 th century.

In 1987, the first case to go to trial using DNA evidence became a global event. The case involved a seventeen-year-old British man accused in two local rape-murders who was cleared only after the DNA of 5,000 men identified the true perpetrator, Colin Pitchfork. The first man to be convicted on DNA evidence also brought the method into worldwide debate. That same year, it seemed as if everyone was in on the debate on whether or not to allow DNA evidence into an American case which resulted in the process to certify and standardize forensic-related quality control guidelines throughout the United States and the world.

By 1989, America decided that DNA evidence was sound and valid, and the first American to be convicted on the basis of DNA evidence was sentenced 25 to 50 years for rape.

The development of a National DNA Index System created by the FBI in 1998 for law enforcement agencies throughout the United States offers both large and small agencies to access and compare DNA profiles from around the country.

Today, a wealth of technological advancements has made forensic investigation a lot easier than it used to be. However, despite such advancements, crime scene investigation still takes a human brain to rationalize and conceptualize what has happened at any crime scene. While forensic investigators rely on such medical and scientific advancements, one must never forget that the human factor comes into play in every crime.

Such basics have not changed for thousands of years, and while forensic science can explain the how of a crime, it can never solve the why. That is up to the crime scene investigator and law enforcement personnel in order to establish motive prior to trial.

It is up to the trained crime scene investigator to take advantage of every scientific and technological development in forensic investigation in order to correctly analyze, retrieve and collect evidence from the scene of any crime.

Crime scene analysis combines the human factor with scientific procedures and methods to interpret what has occurred. While the scientific evidence may speak for itself, it requires human understanding and voices to translate that evidence into a court of law in order to ensure that justice is always served.

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Top contributors

Research Fellow in Ancient History, Macquarie University

Assistant Teaching Professor, University of Missouri-St. Louis

Lecturer, Archaeology, Flinders University

Lecturer in Egyptology, University of Manchester

Professor of Classics, University of Newcastle

Professor of Science Communication and Chemistry, University of Hull

Post-doctoral research fellow in Egyptology, University of Sydney

Postdoctoral research fellow, Griffith University

Head, Public Engagement, Chau Chak Wing Museum, University of Sydney

Lecturer in Classical Studies, The Open University

Professor of Evolutionary Biology, Griffith University

Docteur en Egyptologie, Université Paul Valéry – Montpellier III

PhD Archaeology. Lecturer and Tutor in Ancient World Studies., The University of Melbourne

Experimental Officer and Geophysical Researcher, University of Southampton

Seoul National University

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Associate professor in astronomy, Monash University

Professor of Physics, Monash University

Professor of Biomechanics, University of Hull

Professor of Astrophysics, University of Southampton

Professor of Forensic and Analytical Chemistry, Curtin University

Professor of Human Computer Interaction, The University of Melbourne

Associate Professor of Ophthalmology, University of Massachusetts Medical School

Professor of Astronomy, University of Arizona

Associate Professor of Political Sociology, University of San Diego

Postdoctoral fellow, ARC Center of Excellence for Transformative Meta-Optical Systems (TMOS), Australian National University


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Forensic experts discovery: Secrets of 2,000-year-old Egyptian ‘mummy paintings’ revealed

In the ancient Egyptian settlement of Tebturnis, the modern day Umm el-Baragat in Al Fayyum, scientists believe they have finally uncovered the secrets behind the techniques used to create a series of fifteen “mummy portraits”.

Remarkably, these 2,000-year-old portraits, first unearthed by archaeologists over a century ago in 1899, appear to contain a wide variety of pigments and materials from across the European continent, suggesting that these ancient Egyptian artists had access to a vast, trans-continental trade network.

These masterpieces, created between the first and third centuries AD, were painted onto wooden panels and were intended to cover the faces of ancient Egyptian mummies. It is widely believed that the style of these Roman-era portraits, using bright colors and depicting the delicate features of the figures head-on, originated with the ancient Greeks, and furthermore, influenced the artists of the late-Medieval and proto-Renaissance periods in Europe with their icon paintings of the Madonna and child.

Tebtunis portrait project Photo Credit

Scientists today, using a variety of advanced imaging techniques and pigment analyses, have been able to conclusively situate these works within a larger international context–not just in terms of style but considering the materials used. Archaeologists first discovered that the portraits were sketched out onto wooden panels which came from central Europe.

In studying these, they discovered the use of a bright and costly pigment referred to as Egyptian Blue as a base paint. Given this pigment’s rarity and vivid color, it was often used by artists as the top layer of paint. So why only apply it as a base?

Even more expensive colors like red lead pigments from Spain and iron-earth pigments like yellow ochre jarosite from Kos, Greece, took center stage, Mail Online reported.

These findings, concluded by researchers from Northwestern University and the University of California, Berkeley, provide a unique insight into both the highly-developed trade network spanning the entire European continent and the legacy of the ancient Egyptian artistic tradition. According to Dr. Marc Walton, a materials scientist at Northwestern University and head of the research team there, “these visages of the dead are considered to be the antecedents of Western portraiture” and furthermore, “[the material analysis] provides a fresh and rich archaeological context for the Tebturnis portraits, reflecting the international perspective of these ancient Egyptians”.

The next step for researchers will be to identify the individual artists behind these fascinating works. Walton states that “the specific information obtained from these painting methods and overall distribution of pigments produces groupings of portraits of similar materials, and has led to the identification of ancient workshops and the hand of specific artists”.

The pigments that were used on the paintings
Photo Credit

His team at Northwestern continues to “uncover new and intriguing clues about how to identify the hand of an individual artist”.

In fact, microscopic imaging of brush techniques has already helped researchers to identify a single artist behind three of the fifteen portraits, and they predict that similar discoveries are just on the horizon for the others.

Scientists trial fingerprint development method for Britain's new polymer banknotes

New research into the most effective way of lifting fingerprints from polymer banknotes has been led by scientists at Loughborough University.

In September 2016, the Bank of England will introduce a new £5 polymer banknote into circulation. The following year, the same thin and flexible plastic material will be used for a new £10 note, and by 2020, new £20 notes will also be made available.

Developing fingerprints from this new surface represents an important forensic challenge as current imaging protocols for paper currency will potentially become redundant once the new notes are issued.

This preliminary investigation into the recovery of fingerprints from precursor test notes has successfully demonstrated that fresh latent fingerprints, not immediately visible to the naked eye, can be developed using elemental copper deposited via a highly sensitive technique known as vacuum metal deposition (VMD). The results can then be imaged using near-infrared illumination. In addition, a forensic gelatine sheet can be used to lift from the treated note's surface and then the fingerprints revealed to the naked eye by spraying the sheet with rubeanic acid – a development reagent – which reacts with the copper to produce a visually distinguishable fingermark.

Loughborough University's Dr Paul Kelly, Reader in Inorganic Chemistry, and his research team from the Chemistry Department, collaborated on the study with forensic science equipment suppliers Foster + Freeman Ltd (led by former Loughborough PhD student Dr Roberto King who worked under Dr Kelly) and the Home Office Centre for Applied Science and Technology (CAST).

Dr Kelly's approach means that VMD treated polymer notes may potentially be able to re-enter into circulation rather than having to be destroyed. The gelatine lifting procedure provides a physical record of the development process and marks a further advancement of previous gel applications by Dr Kelly and his research group including combating heritage crime (in the form of metal theft) and the extraction of a chemical blueprint from stone – an early trial of a technique to help address the rising issue of stone theft.

Dr Kelly said: "Our preliminary study into this method of fingermark recovery has demonstrated elemental copper's future suitability for use by forensic examiners in evidence gathering in a variety of situations, from extracting fingerprints from polymer notes used in fraudulent/illegal activities, to linking suspects to stashes of stolen cash or even to forged items.

"The use of the near-infrared illumination procedure is of particular benefit because, allied to the copper deposition, it not only allows visualisation of print, it results in significant ridge detail. The thicker the copper deposition layer, the better the contrast, even on a substrate with a patterned background – and the new polymer notes are decorated with deliberately complex features.

"The next stage of our research will be to see if this new and versatile twist to traditional VMD techniques can be used to enhance fresh fingermarks on other pertinent polymer-based materials, such as carrier bags. We would also like to investigate the possible effect of wear and tear on the VMD development process when analysing handled polymer banknotes.

"In addition, it's worth noting that collaborations like this one, between the University, Bank of England, Foster + Freeman Ltd, CAST, and West Technology Systems Limited, show just how effective joint working can be on what is both a timely and important issue."

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