Laser illuminates artifacts of the past
Painted altarpieces and other artwork that in late medieval times orated Norwegian churches are now unrecognizable because of loss of color and other damages received during the centuries.
Presently however, the art is investigated by the use of lasers, x-rays and more, to reveal what they originally looked like and how they where made.
The Museum of Cultural History in Oslo contains a special collection of church art from the late medieval period; a period stretching from the Black Death to approximately the 1500s.
The collection contains altarpieces, sculptures, crucifixes and relic shrines. Associate Professor Noëlle L.W. Streeton at the Department of Archaeology, Conservation and History noticed that church art was a field of study that hadn’t been examined thoroughly.
Consequently, in 2010 she started an interdisciplinary research initiative to gain more knowledge on the subject.
Noëlle Streeton, with her expertise within conservation, knew that the Department of Chemistry could help with modern tools and new methods not available the last time church art where systematically studied.
Consequently, she contacted senior Engineer Niels Højmark Andersen and Professor Einar Uggerud, and they were immediately interested.
The road was then paved for an interdisciplinary research initiative that involves three faculties at the University of Oslo and several external collaborators.
– We are mainly going to look at late medieval church art conserved by our museums. These artifacts are originally very colorful, but in their present state they have lost a lot of color and are damaged in several different ways. The good news is that there has developed new scientific methods that can reveal more about what the artifacts originally looked like, says Streeton.
Shockingly, 80 years have gone since the last time the museums art collection was systematically studied. The result of these studies is referred to in Eivind Engelstads book “Late Medieval Art in Norway” dating back to 1936.
Lasers reveal hidden information
The scientists are going to use modern scientific methods to study approximately 25 of a total of 65 artworks from the Museum of Cultural History’s collection. Postdoc Elena Platania at the Department of Chemistry is among other things currently studying several of the old artifacts with Raman Spectroscopy.
This technique illuminates the art with a laser beam to study the pigmentation. Raman Spectroscopy is very useful when identifying what materials, for example what type of inorganic pigmentation, were used in the old works of art.
The wooden material in most of the artifacts is oak. The altarpieces and the other church art often have many layers of primer, paint and varnish from both the original artist and later restorations.
– We investigate each individual layer and try to understand how the artist worked and what materials where used. In that way we can create an image of how competent the artist was. Additionally, it can also give us a hint on where the materials – both the woodwork and pigmentation – originated from, explains Platania.
A Mystery of art history
Elena Platania has already stumbled on an art history mystery: In tests from an altarpiece taken from the church at the North-Norwegian Island Skjervøy the Ramen laser revealed a strange mix of the pigments Lead-tin-yellow and Ultramarine, the latter extracted from the rock Lapis lazuli.
– It is strange that this mix was used because Lapis lazuli pigmentation was extremely expensive. As expensive as gold, says Platania.
After discovering this mix of pigmentation in the altarpiece from Skjervøy the scientists have discovered the same mix in art from other Norwegian churches as well. Consequently, all these artworks could possibly be from the same artist community – but where exactly was this community?
– We cannot locate the location of the art workshop based on the pigments, because they are nearly always imported. The only known source of Lapis lazuli in the middle ages was in the area that today is known as Afghanistan. However, what we can do is say something about the workshops location based on impurities because the pigment is mixed with local ingredients, says Platania.
Green trees turn brown
Associate Professor Hartmut Kutzke from Museum of Cultural History contributes to the project with his knowledge on how copper was used in old pigmentation recipes.
– The old church artists used several different pigments combined with copper. Some pigments reacted both with other pigments and the materials used to resurface the woodwork before it was painted, he explains.
Moreover, Kutzke says that the old artworks originally had substantially stronger coloring than they have today. It is fairly common that copper pigmentation reacts with the primer and loses color, for example making green trees turn brown after a few years.
The scientists also want to understand why copper pigmentation flakes off and loses color some places while other places keeping fully intact.
«CSI: Church Art Edition»
The art works are also going to be investigated using x-rays, dendrochronology and with ultraviolet and infrared photography.
– In the future we will also study the artworks using scanning Electron microscopy. Additionally, we will investigate in what way the visible color on the pigments effect the surrounding materials. We will use a modeling technique called computational quantum chemistry that can predict which color spectrum the different pigmentation mixes and excipients can create, explains Einar Uggerud.
The scientist participating in this project is actually using a lot of the methods made famous by the popular TV series Crime Scene Investigation (SCI).
The CSI investigators want to find out «who has done it? » and «what really happened?». We do too, says Platania.
– Yes, why not call us “history’s equivalent to CSI”, says Streeton. And continues:
– When we have completed this project we will have come closer to unraveling the mysteries that surround these works of art. We will know more about why the green coloring flakes off and we will know more about where these works of art where produced. Already we know the following: A new report from an expert in dendrochronology at the National Gallery of Denmark has proven that three of the artworks from the Skjervøy Church were painted on oak imported from the Baltic, she explains.
– In summary: We hope this Research Project can increase our knowledge on how these timeworn works of art looked when they were brand new, how they were constructed and maybe something regarding the location of the artists behind them as well, says Streeton.
The research project 1350-1550: Painting and polychrome sculpture In Norway succeeding the Black Death is located at Department of Archaeology, Conservation and History at UiO.
The project includes scientists from Museum of Cultural History in Oslo, the Faculty of Mathematics and Natural Sciences and the Faculty of Humanities at UiO, in addition to Sintef, the Norwegian Geotechnical Institute and the Centre for Art Technological Studies and Conservation (CATS) in Copenhagen.
The project is funded by the Norwegian Research Council through the initiative Independent basic research projects - Humanities and Social Sciences (FRIHUMSAM).
(Translated from Norwegian into English by Espen Haakstad)
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