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Polychrome Artefacts Lab

Our heritage is full of colour. The use of colour to finish sculptures and objects in wood, metal or stone, both in buildings and outdoors, is called polychromy. We study these layers to know more about our past and discover how to preserve these unique objects for the future.

What do colour layers teach us?

The pictorial layers on heritage items harbour a wealth of information. Unexpected discoveries, such the use of flour in the ground layer of a painting by Rembrandt, can attract worldwide attention!

Our researchers have the essential knowledge and tools to:

  • identify the composition of layers (pigments, dyes, binders, varnishes, additives)
  • determine each layer's function in the stratigraphy or layer structure (preparation, insulation, gilding, underlayer, glaze)
  • analyse the interaction and transformation of materials during the aging process (discolouration, fading or swelling, or even the formation and accumulation of degradation products such as metallic soaps and oxalates or sulphates)
  • gain an insight into the methods used to prepare pigments (raw materials, quality grades, counterfeiting).

Maximum preservation of the original materials

The colour layers we study are inseparable from the object to which they are applied. The item in question is often a unique piece of heritage or a valuable work of art.

In addition to non-invasive methods, which do not require sampling, our scientists also use non-destructive analyses. In this way, the micro-sample of a work of art is not damaged, and the colour layer remains intact.

Dr Francisco Mederos-Henry, chemist: "We aim to minimise the amount of material needed for exact identification. We are therefore constantly improving the available techniques, such as HPLC-DAD or ATR-FTIR. We are getting better and better at this, thanks to our multi-instrumental approach combined with our specialised expertise in micro- and nano-chemical analyses."

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Understanding chemical transformations

Through our research projects and studies, we learn more about past technologies. At the same time, we develop new insights and techniques to better protect works in the future.

Dr Jana Sanyova, head of the lab, explains: "Some good examples are the masterpieces by Romanesque sculptors or the Flemish Primitives. These are valuable heritage items that we want to preserve for generations to come. But light, humidity and cleaning can cause chemical transformations in the pictorial material. This creates, among other things, metal oxalates that result in a grey veil. Thanks to the MetOx project, we are on the right track to understanding this phenomenon."

Experience and network

For decades, the Institute has been studying the interactions between the constituents of pictorial layers, how they are prepared and processed and their degradation phenomena. These studies sometimes need to be supported by highly sophisticated analytical methods, which involves making use of our extensive network of contacts. We are particularly proud of our good cooperation with renowned institutions both at home and abroad:

  • universities: University of Antwerp, UCLouvain, University of Amsterdam, Royal Danish Academy (KADK), University of Chemistry and Technology, Prague, etc.
  • research institutes: European Synchrotron Radiation Facility, Doerner Institute, etc.
  • museums: the National Gallery in London, Rijksmuseum in Amsterdam, Berlin State Museums, Kunsthistorisches Museum in Vienna, etc.
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Would you like to request a study? Contact us for initial advice or a free estimate.

Our experts

Cécile Glaude
Sophie Kirkpatrick
Francisco Mederos Henry
Martina Stillhammerova

We will be pleased to guide you in the choice of the most suitable analysis technique or study.

Request a free quote by e-mail or telephone.

Consult our price list

For complex studies, we come on site in advance to determine the price.