Conservation

Conserve and restore art & cultural artifacts using Bruker's analytical instrumentation.

Both XRF (hand held, portable and mobile) as well as vibrational spectroscopy techniques such as NIR, FT-IR and Raman spectroscopy are non-invasive and non-destructive techniques ideally suited for the study of art and museum (cultural heritage) objects

Whereas XRF provides the elemental (qualitative and possibly quantitative) information, IR and Raman provide information on functional groups and compounds in the material.

XRF

With XRF, the conservator investigates for example, the layering of materials such as paint layers. The elemental fingerprint helps with identification of the pigment and glazes and can help with the authentication of objects.

Liberty Bell investigation
TiO2 in paint

When the conservator combines the elemental XRF information with the Raman spectral fingerprint, it is readily possible to identify the exact pigment as well as the oxidation state of the elements. This knowledge enables the curator to select appropriate methods for the conservation and restoration of the analyzed object.

Della Robbia blue glaze:micro-Raman temperature study and X-ray fluorescencespectroscopy characterization

Infrared

With portable IR, it is possible to analyze and identify gemstones as well as identify stains and materials on cloths.

Gemstone from Diego Sali
Sweden monarchy clothes

Raman

Raman spectroscopy can identify pigments (e.g. the mineral from which the pigment is derived) and with the proven micro spot Raman microscope SENTERRA II, the colorants of single fibers (Marco Leona article). Raman spectroscopy also allows the imaging of an area by “scanning” the area using a XY stage of the microscope.

In many cases, changes in the pigment structure (e.g. by oxidation) lead to complete color changes such as from red to brown in the aging of mercury based pigments. This is problematic when previous restorations were done by over-painting the area with an ochre based brown pigment instead of using the original red.

Natural History

Natural History collections face other issues which can be readily addressed with HH XRF. In the past, the many chemicals used for the conservation of animal hides and taxidermy contained hazardous elements such as Pb, As, Hg and Cd. These could be released into the air or transferred to visitors who touch the objects. This also affects the health of the custodial and conservation personnel. With HH XRF, the object to be checked can be measured in situ. The HH XRF is placed in contact with a tripod and using the attached PC, the analyst can immediately identify the possible hazardous elements. Also, heirlooms such as bison head which was found in Oklahoma can be readily tested and one can rest assured.

Handheld XRF testing of a mounted red fox

Handheld XRF testing of Tasmanian devil hide

Elemental, layering and comparison

Using both the elemental fingerprint and layering information as well as comparing the original pigment with the altered pigments enables the curator to select the best practice for the conservation of the object.

Imaging

Using area imaging techniques, the before mentioned methods can be used with a small spot, which can be as small as a couple of microns in Raman and 25 microns or 70 microns when using XRF. The portable open beam micro-XRF BRUKER ARTAX can image paintings in situ, whereas the smaller spot M4 TORNADO enables the imaging of objects which fit into the radiation-safe compartment. The M4 was used to image the backside of a painting in the Museum of Fine Arts in Leipzig, Germany, where a second unfinished painting of the painter Max Klinger was discovered using micro XRF.

Painting by Max Klinger

The ARTAX is extensively used by major American museums as part of their acquisition and conservation process. Using XRF techniques also enables conservators to so see if paintings were changed by the artist or edited by later conservation efforts.