Archive for the ‘Modern(ish)’ Category

Stolen Van Gogh “proof of life” pics circulate

Monday, June 29th, 2020

A “proof of life” picture of the Van Gogh painting stolen from a museum in March has emerged. The photograph shows the painting topped by a May 30th issue of the international edition of the New York Times on one side and a book on the other. The book is Meesterdief by Wilson Boldewijn, a biography of one of the art thieves who stole two paintings from the Van Gogh Museum in Amsterdam in 2002. A second photograph shows the label on the back of the painting.

(The choice of book is obviously pointed, the art crime version of a weird flex. One of the two paintings stolen in 2002 was Congregation Leaving the Reformed Church in Nuenen, a different scene of the same church where Van Gogh’s father was minister. Both paintings were found outside of Naples in 2016 after having been passed around as currency in a Camorra organized crime network for years.)

The Parsonage Garden at Nuenen in the Spring (1884) was stolen from the Singer Laren Museum outside Amsterdam in the early hours of Monday, March 30th, what would have been Van Gogh’s 167th birthday. The smash-and-grab raid targeted the painting which was on loan from the Groninger Museum. The thieves broke in through the glass door, took the painting and fled before the police could arrive.

These are almost certainly photographs of the authentic work. The image of the label on the back of the painting is particularly telling because as far as Andreas Blühm, Director of the Groninger Museum, knows, no photograph of the label has ever been published before.

The images were received by Arthur Brand, a private eye who specializes in retrieving lost art works. He is not naming his source, but he has extensive knowledge of and connections to the art crime underworld. He has seen more than these two pictures of the stolen painting, so it seems that the thieves are circulating these snapshots to find a buyer.

“In some cases when art is stolen, the thieves get nervous, they can’t get rid of it or they think the police is on their tail so they destroy it,” [Brand] told The Associated Press in a telephone interview. “So these pictures show that we are dealing with professionals. So the painting is still alive, I wanted to say.”

Brand said he had shared the photos with police investigating the theft.

Police spokeswoman Laetitia Griffioen said the photos “are part of the investigation.” She declined further comment.

Professionals though they may be, they are not handling their cash cow with anything like appropriate care. From the photo, it looks like the painting is on a garbage bag and the newspaper and book are casually plopped on top of its unprotected surface. There is also a white mark in the bottom center just below the fence posts. It could be a scratch because the original painting was done on paper and later mounted on board.

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Norway ship burial excavation begins

Saturday, June 27th, 2020

On Friday, June 26th, Norway’s Minister of Climate and Environment Sveinung Rotevatn broke ground on the country’s first excavation of a Viking ship burial mound in 100 years. The newly-discovered Gjellestad Ship comes slow on the heels of the Oseberg Ship which was excavated in 1904. Archaeological methodology, technology and understanding is a completely different universe 116 years later, so even though the  Gjellestad Ship is known to be in a far worse state of preservation than the exquisite Oseberg (now on display at the Viking Ship Museum in Oslo), methods like micromorphology, DNA analysis, soil analysis and stable isotope analysis will give archaeologists a far richer picture of the ship burial, its contents and context.

The Gjellestad ship was discovered during a ground penetrating radar scan of a field in Halden, southeastern Norway, in October of 2018. The GPR picked up the distinctive shape of the 65-foot long ship set within the circular perimeter of what had once been a burial mound on top of it, lost over centuries of agricultural work. It was incredibly close to the surface, just 1.6 feet underground, and therefore incredibly close to destruction.

In September of last year, Norwegian Institute for Cultural Heritage Research (NIKU) archaeologists dug a test pit and retrieved a sample of the wood from the keel to get an idea of the ship’s age and condition. There was good news and there was bad news. The good news was the ship was confirmed dendrochronologically to be a Viking ship, the timber for its keel felled between the late 8th century and the start of the 10th century. The bad news was it is being devoured by fungal growth and very close to destruction.

Norway allocated funds for an emergency excavation of the Gjellestad Viking Ship to recover whatever of the ship and its context can be recovered before it all rots away. Now that the official ground-breaking is out of the way, archaeologists will begin the official excavation on Monday. Stage one entails the painstaking sifting of all the topsoil above the ship to a depth of about one foot. The hope is there might be some iron rivets, boat fittings, artifacts that were churned up out of their original positions by ploughing.

The ship is bisected by a drainage ditch, so the team is taking advantage of the landscape in the project planning. Working under a protective tent that covers the entire length and width of the ship, the team will first excavate the bow which is about 23 feet long tip to drainage ditch. In the second phase of excavation, they will unearth the bow and the burial chamber which is expected to be about in center of the ship.

The team is hoping to find grave goods, but there is evidence that the mound was looted long ago. Grave robbers dug a tunnel down the center of the ship so all the more obvious portable wealth like precious metals and jewelry from the burial chamber is probably gone. On the plus side, utensils, household goods, pottery and the like placed in the bow and stern were likely left behind.

The full excavation is expected to take about five months. It will not be open, but archaeologists will plan guided tours, pandemic measures permitting.

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17th c. children’s cemetery found in Poland

Friday, June 26th, 2020

Archaeologists have unearthed the remains of more than 100 children in a late 16th, early 17th century graveyard in the village of Jeżowe, southeastern Poland. Human remains were first discovered by road workers and archaeologists called in to excavate. They have found the skeletons of 115 individuals, most of them, around 70-80%, are of children.

Many of the burials unearthed thus far can be precisely dated despite the lack of grave markers because the deceased were buried with coins in the mouths. Most of the coins were minted during the reign of Sigismund III Vasa who ruled Poland from 1587 to 1632. There were also coins from John II Casimir Vasa (r. 1648-1668).

It’s the “pay the ferryman” aka Charon’s obol tradition, a funerary practice common in ancient Greece and Rome. Coins were placed in the grave so that the souls of the dead would have cash to pay Charon to ferry them across the river Styx to the Underworld. The practice was not uniform — the number, placement and type of coins differed from place to place and culture to culture — but it was widespread in the Greco-Roman world and the Near East. It was adopted by local peoples in late antiquity and continued into the early Christian era. There were still instances of it as recently as the 20th century. While the ritual was interpreted differently depending on time and location, there are clusters of finds in which the practice was consistent between burials. The coin being placed in the mouth is more frequently seen in Christian burials from Merovingian France to 19th century Britain.

The burials in Poland contained no other grave goods, nor any evidence of hardware like coffin nails or fittings. This indicates the cemetery was used by people of modest means.

[Archaeologist Katarzyna] Oleszek said, “We know from sources that during a visit of the bishops of Kraków here in Jeżowe 1604 there was already a large parish church, with a garden, a rectory, a school and a cemetery. It probably existed already since 1590.”

The bodies were found in sandy ground and were arranged on an east-west axis, all with heads to the west on their backs with the hands at their sides. The graves are most likely those from the children’s section of the graveyard.

One grave contains the bodies of four children. They lay in close formation but not on top of each other. All their heads are resting to one side in the same direction. The fourth child, on the edge of the group, is much younger than the others.

“The arrangement of the skeletons, the state of their preservation, shows that the discovery is a Catholic church cemetery, which was certainly taken care of. No grave is damaged by another. The inhabitants knew exactly where they had graves and took care of them,” said Oleszek.

There is no more church at the site, only a small memorial chapel marking the spot. The remains will be fully exhumed and studied before reburial at the current parish church.

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Summer solstice at Pompeii

Tuesday, June 23rd, 2020

The sun was hiding behind the clouds up at Stonehenge this year, but it was a lens-flarin’ spectacle at Pompeii.

The Via di Nola and Via dell’Abbondaza face the sun at summer solstice. They are aligned within less than half a degree of the solstice sunrise azimuth. This is a feature seen in other Roman cities, including Pompeii’s neighbor Herculaneum. Ancient writers record that it was customary to orient a town’s main street, the Decumanus, towards to sun where it rises on a day of special significance to the town. Solstice sunrise was a special day for many Roman towns and forts. Archaeologists suspect the origins of the practice goes back to the Etruscans whose religious rituals the Romans absorbed.

Already at the beginning of the last century, antiques and archaeological research investigated the urban orientation of Pompeii and its relationship with astronomical orientations and the sun. As part of the wider program of studies on the cities of Campania, the doctoral course of the Department of Letters and Cultural Heritage of the University of Campania, combining astronomy and archeology and moving from scientific data, investigates the ancient urban systems, from Capua to Calatia to Sorrento. The Archaeological Park of Pompeii opened its doors shortly before dawn to the small group of scholars composed of Carlo Rescigno, Michele Silani, Carmela Capaldi and Ilaria De Cristofaro. The sun, on the day when it ‘stays’ longer in the sky, arose from the tip of the mountain on Via di Nola and dell’Abbondanza and from these streets it was photographed in its blinding halo. The city of Athena and Apollo, of Diana and Venus, is also told by the lines, apparently silent, of its many orientations. And documenting the city, the summer solstice was celebrated in a Pompeii illuminated by the first light of dawn, immersed in history and in its many possibilities of knowledge.

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Rare whale bones found in Leith

Monday, June 22nd, 2020

Two bones from a whale that may date as far back as the medieval period have been discovered in Leith, Scotland. Archaeologists surveying the site of a new tramway unearthed the rare bones earlier this year between the post office and a scrap yard on Constitution Street. They are the radius and ulna from the fin of a large adult male sperm whale and are a matched pair. They have not been radiocarbon dated yet because a pandemic rudely got in the way, but the archaeological context suggests they could be as much as 800 years old, dating to the earliest days of Leith’s settlement.

Located at the mouth of the Leith river on the Firth of Forth coast just north of Edinburgh, Leith has served as the city’s major port since the 12th century. Shipbuilding and whaling were two of its major industries from inception, the latter continuing well into the 1960s when ships had to go far afield to Arctic and Antarctic waters to find any whales left to kill.

Amongst possible theories are that they were brought back in the 19th or 20th century as a memento as part of Leith’s historic whaling industry, that they came from the remains of a whale beached locally and were subsequently dumped there or that they were part of medieval deposits left there during the reclamation of the site in the 17th to 19th centuries, perhaps dating back to the medieval period.

Other finds of note made during the exploration include an iron cannonball likely dating to the 17th century when the defenses of this area of Leith were reinforced during the Civil War, the remains of large stone wall that may have been part of a seawall built in the 16th or 17th century.

When the archaeological work began in November 2019, the team took down a wall from a graveyard that was established on the site in 1790 and in so doing discovered a large charnel pit with tightly stacked bones. This was probably created when graves were disturbed during the construction of utilities on Constitution Street in 19th century. The graveyard itself will be excavated later this year.

City archaeologist John Lawson said: “Our work to excavate the area as part of preparatory work for the Trams to Newhaven project has offered really interesting glimpses into the area’s history, over the past three to four hundred years, and we’re endeavouring to conserve that.

“Discoveries like the whale bones have been particularly fascinating and exciting. These bones provide a rare glimpse into and also a physical link with Leith’s whaling past, one of its lesser known maritime industries and one which in the 20th century reached as far as the Antarctic. Given the circumstances of how they were found it is possible that they may date back to the medieval period, and if so would be a rare and exciting archaeological discovery in Edinburgh.”

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Hercules Segers motherlode online

Thursday, June 18th, 2020

Visionary printmaker of the Dutch Golden Age Hercules Pieterszoon Segers (ca. 1589 – ca. 1638) inspired artists whose names are much more famous than his today, most notably Rembrandt van Rijn who was an avid collector of Segers paintings and prints. Very few Segers works are known to survive today — 183 unique impressions from 53 plates and 18 paintings — and the Rijksmuseum has the largest single collection of them with 74 impressions, two oil sketches and one painting.

Segers’s prints are at the heart of the artist’s later fame. With an array of techniques whose identification has puzzled artists and scholars alike, he etched unusual colourful landscapes, seascapes, biblical scenes and other subjects. Rejecting the idea that prints from a single plate should all look the same, he produced impressions in varied colour schemes, on grounded paper or textiles, colouring his prints with the brush and altering his etching plates by adding lines in drypoint. Employing a variety of unusual techniques and materials, he turned each impression of his etchings into an individual work of art.

The collection formed the core of the landmark Segers retrospective exhibited at the Rijksmuseum in late 2016, early 2017 and subsequently at the Metropolitan Museum of Art in New York City. That exhibition brought together almost all of the extant works known to exist today, including 110 prints and all 18 paintings. In preparing for the retrospective, researchers, scientists and art historians at the Rijksmuseum carried out an unprecedented in-depth study of Segers’ works. The study, which revolutionized understanding of his highly experimental techniques, was published in a new comprehensive oeuvre catalogue in 2017.

The Rijksmuseum has now made much of that information available for free in a new online collection catalogue. All of the museum’s Segers pieces can be viewed in the glorious high resolution to which the Rijksmuseum has made us accustomed with entries summarizing the results of the research and lending new insight into the artist’s process, materials and the dates of his works. The catalogue entries include all known information about the works from measurements to techniques to inscriptions and collectors’ marks usually found on the versos of prints. There are also links to works in the Rijksmuseum, other public collections and private ones that are connected in some way to the Segers prints.

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WWII silver cache found in 14th c. castle

Wednesday, June 17th, 2020

A hoard of silver objects likely buried in World War II has been discovered on the grounds of a 14th century castle in Nowy Sącz, southern Poland. A group from the Nowy Sącz Historical and Exploratory Association were surveying a site near the castle tower when their metal detector alerted them to the presence of what turned out to be a rusted out chest. The crate was corroded almost to nothingness, but the treasure it contained was in excellent condition.

They first unearthed some paperwork — apparently passes and receipts — in poor condition. Under the pages the chest was filled with silver tableware, including goblets, stemware, cups, flatware, serving vessels and candlesticks. In total 103 silver objects were found in the disintegrating chest. The pieces date from the turn of the 19th-20th centuries and the design style identifies them as Jewish ceremonial art.

Local archaeologist Bartłomiej Urbański, who was present at the search site, said: “It is Judaica, probably from the turn of the 19th and 20th century, connected to Jewish ritual and was probably buried during World War Two.

He added: “Is it connected with the buildings that used to be in this part of the city, or was it stolen by the Germans, who were then unable to take it away?”

The town of Nowy Sącz was founded by Wenceslaus II of Bohemia in 1292, eight years before he became King of Poland. Its location near an important trade route to Hungary garnered it significant privileges. Wenceslaus replaced a wooden watchtower perched on a hill within the city’s fortifications with a castle. In the mid-1300s, King Casimir III the Great greatly expanded the royal castle, integrating it into the new defensive wall he had built around the city. This grander castle of Nowy Sącz had two corner towers, at least one other tower, a residential building with multiple stories, and probably a moat separating it from the city proper. For the next 300 years, Polish kings and queens and visiting Hungarian and Danish royalty stayed in the castle. It was devastated by fire twice, once in 1522, once in 1611. After the second fire, the castle was rebuilt and expanded again in Renaissance style by Count Sebastian Lubomirski and, after his death, by his son Stanisław. That phase ended in 1655 when the castle took heavy damage during the Deluge (Sweden’s invasion of the Polish-Lithuanian Commonwealth). It was patched up a couple of times by Austrian authorities after the Partition, but it never really recovered.

It was rebuilt again on a much smaller scale in 1938 just in time for the Nazi invasion of Poland. German forces occupied the castle and used it as a barracks. Under German occupation, 20,000 Nowy Sącz Jews were forced into a ghetto. The ghetto was liquidated in 1942 and all of the town’s Jewish community was sent to slaughter in Bełżec extermination camp. German forces stored large quantities of ammunition at the castle and Polish resistance fighters blew up the depot in 1945, destroying what little was left of the castle. The tower was reconstructed one more time in 1959.

After so beleaguered an existence, only a smattering of walls a few feet high remain of the original 14th century structure. The town of   Nowy Sącz wants to rebuild the castle (yes, again) and convert the tower into a museum. The Sądecki Regional Development Agency contracted with the Nowy Sącz Historical and Exploratory Association to explore the castle ruins assisted by professional archaeologists. They were scanning for shrapnel and metal parts from the explosion when they discovered the silver cache.

The objects will now be transferred to archaeological conservators who will clean, conserve and catalogue them for future display in the local museum.

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Happy birthday, Alfa Romeo!

Monday, June 15th, 2020

Venerable automaker Alfa Romeo celebrates its 110th anniversary in less than 10 days. In honor of the occasion, the company has released an e-book about its history from car models to its iconic logo incorporating the famous dragon eating a man, the emblem of the Visconti family which once ruled the city of Milan.

The first car was manufactured in 1910 when the company was still an acronym, A.L.F.A. (Anonima Lombarda Fabbrica Automobili, meaning “Lombard Automobile Factory, Public Company”). The 42 HP could reach an impressive-for-the-time top speed of 62 miles per hour. Fifty of them were sold in the first year. The engine was strong enough to power a prototype biplane made of bicycle tubes.

A.L.F.A. built on the success of the 42 HP and quickly grew. By 1915 it had 2,500 employees manufacturing three models. Then came World War I. The factory was converted to wartime production — aircraft engines, munitions, compressors — until 1919 when Alfa resumed car production. With the new cars came a new name as Nicola Romeo, an engineer and entrepreneur who had acquired a majority of shares in 1915 and all of them by 1918, added his name to the brand. The first car to come off the line bearing the Alfa Romeo imprimatur was the 1921 Torpedo 20/30 HP.

This was the decade when Alfa made its bones in racing. Its first racing team included a certain Enzo Ferrari as a driver. Alfa’s innovations won it the most prestigious races of the time, the Le Mans, Mille Miglia and a myriad Grands Prix. They also made for some amazing looking cars, ones like the Tipo B Aerodinamica (1934) and the 8C 2900 Le Mans (1938) that wouldn’t be remotely out of place in a superhero’s secret cave lair.

Automobile production came to a halt again during the Second World War, but when it resumed in April 1945, it resumed with a bang. The first post-war Alfa Romeo was the Freccia d’Oro (Golden Arrow) produced in 1947 and beloved by crowned heads and Hollywood stars alike. Icons like the Spider and Giulia followed.

But it’s the prototypes that thrill me the most. The 1952 prototype Disco Volante (“flying saucer”) really does look like it should be dropping from the belly of a mothership. The greatest discovery in this ebook for me, however, is the 40-60 HP “Aerodinamica,” which was a private commission from Count Marco Ricotti in 1914. It was made entirely of lightweight aluminum and was shaped like a torpedo with porthole-style windows. The chassis and engine were exactly the same as the ones in the 40-60 HP production series, but the body was a pioneering attempt to harness the principles of aviation design for a land-going vehicle. It could reach a top speed of 86 mph, 12 miles faster than the standard 40-60 HP, thanks to its unique body confirmation. The tear-drop shape earned it the moniker Siluro (“torpedo”) Ricotti.

Alas, Count Ricotti chose … poorly. He had the car modified, some might say butchered, into a goofy roofless excursion vehicle. What was left of it after that did not survive. Alfa Romeo sought to remedy this cruel state of affairs and in 1979 commissioned an exact replica of the great Siluro recreated from the original designs. Recreating that torpedo body was more challenging as it had been produced by a separate company, the Carrozzeria Castagna, and no original designs for it exist. The Carrozzeria Castagna did have a photo in its archives of the Siluro’s manufacture, which gave the reconstruction team the information needed to replicate an accurate skeleton and external form. The new Siluro, a copy of the original in all its details including the unbelievable “damascene” finish of the aluminum, is now on display at the Alfa Romeo Museum in Arese, Milan. The museum reopens after the long Italian lockdown on June 24th, Alfa Romeo’s 110th birthday.

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The Maya wall paintings from Chajul, Guatemala

Saturday, June 13th, 2020

A study of early Colonial wall paintings found in private homes in Chajul, Guatemala, has revealed they were painted by local Ixil Maya artists using a combination of traditional techniques and European motifs. They are rare surviving glimpses into the shift in cultural practice and iconography from the pre-Hispanic Maya to the Spanish Colony.

Chajul was an important regional center before it was conquered by Spain in 1530. A vase from the Late Classic period (600-800 A.D.) names a high official of the Chajul king, so it was a politically prominent city with its own dynasty of rulers. Most of the ancient city is believed to lie underneath the modern city, with only a few Maya structures marking the perimeter of a ballcourt found northwest of modern Chajul.

Colonial-era murals were first discovered in Chajul during a house renovation in 2003 and archaeologists from the Institute of Anthropology and History of Guatemala (IDAEH) determined they dated to the Colonial period (1524-1821). The largest and best-preserved wall paintings were discovered in the home of the Asicona family who still live there today. It was dubbed House 3.

House 3 is an adobe brick structure bound with a mixture of pine needles and mortar. The interior walls were covered with white stucco and murals painted on the surface. The presence of old murals was first detected in the 1990s but they were only small glimpses of the still-hidden whole. It was only when owner Lucas Asicona Ramírez removed the outer layers of plaster on the wall in the course of replacing the roof that the full surviving murals were revealed.

The murals decorate the north, east and west walls of the central room of House 3. The original south wall was demolished long ago, but it probably had murals as well. They depict musicians playing instruments, both local and Spanish-introduced, dancers, some wearing European clothes, some wearing mixed Indian-Spanish fashions. Chajul locals believe the murals represent dances, either the Baile de la Conquista (Dance of the Conquest), or the Baile de los Moros y Cristianos (Dance of the Moors and Christians), which are performed stories from the Spanish conquest of the Maya highlands.

In 2011 almost all the houses with murals were photographed and documented. In 2014 the large, well-preserved murals in House 3 were 3D laser-scanned. In 2015, Polish researchers undertook a physical and chemical study and conservation of the extensive murals in House 3.

Using techniques including scanning electronic microscopy, X-ray powder diffraction and gas chromatography-mass spectrometry, researchers found that the methods and materials used to make the murals were the same ones used for centuries before the Spanish conquest. The color palette is type of pre-Hispanic Maya wall paintings found in the Maya Lowlands — white lime, ochre, Maya blue. The blue no longer looks blue today; it’s more like grey. The fading was caused either by a conservation problem, and/or a decline in the color-fastness of the pigment due to the loss of traditional knowledge about how to prepare it, specifically which mineral was the source of the blue color and what temperature to heat it. The underlying stucco is also the same type — local calcium carbonate mixed with ground seashells — as the stucco in widespread use during the Maya Postclassic period.

Our research to date, including interviews with Chajul inhabitants about local history and tradition, suggests that houses with murals were originally owned by important members of the local community—possibly members of the cofradías. These individuals were involved in the organisation of religious events, both those connected with Catholicism and those linked with costumbre (or Maya spirituality, related to the cult of the Maya pre-Columbian calendar and to agrarian rituals). Prior to the recent civil war in Guatemala (c. 1960–1996), there were approximately 10 cofradías in Chajul, although their number has decreased in recent years. The rooms with paintings probably served as places for important cofradía meetings and dances (cf. Howell 2004: 35).

Although the murals are currently located in domestic spaces, it is possible that in the past, painted rooms (or whole houses) might have played a different role. According to Lucas Asicona, the three rooms of house 3 had different functions in the early twentieth century. The northernmost room served as a space for receiving visitors; the central room, with the murals (at that time completely covered by later stucco), served as a place for special events, such as meetings, ceremonies and dances for the cofradía. Finally, the southernmost room was a kitchen and living room. A large patio in front of the house provided another space for dances. This division seems to reflect the original seventeenth-/eighteenth-century layout and function of the house. It should be noted that some other Chajul city houses with wall paintings have been—or still are—used as meeting places for cofradía members. Thus, it is very plausible that most, if not all, of the houses with murals belonged to cofradía members and served as important places for meeting and dance. As such, the paintings from these locations may commemorate special events, particularly dances, practised by these important religious and social organisations.

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Inorganic lead white pigment radiocarbon dated

Friday, June 12th, 2020

As plants and animals absorb carbon dioxide during their lifetimes, they absorb the unstable isotope carbon-14 with it. When they die, the carbon exchange stops and the C14 isotopes start to decay at a steady rate. Radiocarbon dating works by measuring the amount of carbon-14 present in organic archaeological materials and comparing it to reference standards. Now for the first time, researchers have been able to radiocarbon date an inorganic pigment to date wall paintings from the Late Middle Ages. This breakthrough technique makes it possible to get absolute dates for paintings from antiquity through the 19th century, a huge boon to conservators, art historians and authenticators.

Paintings made before the 20th century usually incorporate organic ingredients like vegetable oils or egg binders, but binders are often contaminated over the years by varnishes and retouches and the carbon content is too low to test. The wood of panel paintings, the wood supports of canvas paintings, the canvas itself can be radiocarbon dated and indeed frequently are in authentication investigations, but the C14 information pertains to the date the wood or plant was harvested, not when the painting was made per se.

Murals have no organic backings or binders, so the only possible route for absolute dating are the pigments in the paint layers themselves. Most ancient pigments have no carbon content. Only carbon black, made from charcoal, has been radiocarbon dated before.

Two widespread white pigments – calcium carbonate and lead white – are carbonate-based pigments and contain carbon. Both are considered as mineral pigments, but are produced differently. Calcium carbonate (CaCO3) is a natural pigment extracted from quarries. It was formed several million years ago from micro-organisms, but due to the 14C radioactive decay of 5700 years, geological CaCO3 no longer contains enough 14C to be radiocarbon dated. Conversely, lead white is synthesized. Lead white, composed of cerussite (PbCO3) and hydrocerussite (Pb3(CO3)2(OH)2), has been artificially produced by lead corrosion since Antiquity. This corrosion process, involving metallic lead, vinegar and organic substances such as horse manure or tan bark, was also named the stack or Dutch process when mass production started from the 16th century on.

Lead white was widely used by painters from antiquity to Van Gogh, so being able to derive an absolute date from the pigment would open up all kinds of new possibilities. The trick was to develop a technique to separate the carbon in lead white that would leave it uncontaminated and testable. The research team devised a thermal separation system that heated the sample to 400 °C, high enough to break apart lead carbonates but low enough for the carbon release process to be monitored and controlled.

Researchers deployed the process on samples of wall paintings from the 14th century dressing room of Margaret of Bavaria in the Château de Germolles in Burgundy, and fragments from the medieval rood screen of the Church of the Cordeliers in Fribourg, Switzerland. The rood screen was destroyed in 1745 and the rubble used as fill to raise the floor for a new pavement. A 1985 restoration removed the floor and recovered 14,000 painted fragments.

The radiocarbon dates of three samples from the Château de Germolles are 1292–1401, 1283–1397, and 1300–1419. The nine fragments of the Cordeliers rood screen range in date from 1262 to 1630. These results are all consistent with the known history of the château and the church.

In this study, we demonstrate that it is possible to extract all the carbon from lead carbonates by thermal decomposition in order to date lead white pigments and paintings by the radiocarbon method. The synthesis process of lead white is identified according to the 14C content and we show that the 14C isotope is therefore an important marker for reconstructing the history of lead white production. The process most commonly used over time is the corrosion process occurring in a fermenting environment. Metallic lead and vinegar were placed in pots embedded in horse manure or other organic substances. By fermentation, organic substances degrade and release CO2 that carries 14C. The organic substance are thus the key component to obtain a reliable and absolute radiocarbon date. Medieval paintings are a perfect example showing that recipes reported in historical manuscripts were applied. The radiocarbon measurements date the pigment production and provides new insights into the creation of the wall paintings.

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