Report on how the Fitzwilliam Museum Uses NIR Spectroscopy for Pigment Analysis

Analytik report on the exciting “COLOUR: The Art and Science of Illuminated Manuscripts” exhibition at the Fitzwilliam Museum, University of Cambridge. Amongst various analytical instruments, the ASD FieldSpec 4 system was used to characterise both inorganic and organic materials (pigments and binders) on a number of illuminated manuscripts.

 

Amongst various analytical instrumentation chosen to study these illuminated manuscripts and discover their secrets, the ASD FieldSpec 4 Vis-NIR spectroradiometer is highlighted here. The instrument was used to characterise both inorganic and organic materials (pigments and binders) on a number of illuminated manuscripts. The FieldSpec 4 has an extended operating range (350-2500 nm) and this is the key to the success of using this analytical equipment. It is the inclusion of the NIR region (1001-2500 nm) that allows for the analysis of some of the vibrational overtones and band combinations due to functional groups such as hydroxyls, carbonates, and potentially methylenic and amide groups associated with paint binders. For example, one can easily separate green malachite from mixtures of organic yellows and blue azurite. Both being copper carbonates, malachite and azurite are completely indistinguishable by X-ray fluorescence but the latter shows characteristic absorption bands at 1495, 2285, and 2350 nm.

 

Speaking of the FieldSpec 4 spectroradiometer, Dr Paola Ricciardi, a Research Scientist at the Fitzwilliam Museum: “The technical specifications including its high sensitivity and high spectral resolution make it the optimal tool to investigate thin and often complex paint layers. The rapidity of acquisition in addition to the instrument's compactness and portability allow surveying a large number of objects directly in exhibition Galleries or storage rooms. It may also yield a substantial comprehensive data set in a short period of time. This allows carrying out large-scale surveys, acquiring spectra on both test panels and works of art. The data then can be interpreted and used to both answer some of the art historical questions raised in the initial phase of the research and to inform subsequent phases of the analysis, during which the characterisation of the materials can be completed, when needed, using supplementary analytical methods such as Raman spectroscopy, XRF, and others.”

 

Speaking about the exhibition, Analytik's Product Specialist, Adrian Waltho, said: “Seeing ancient manuscripts presented so beautifully was a real pleasure, and the science behind pigment identification with NIR spectroscopy is always fascinating. Having them together side by side was incredible and really brought the exhibition to life.”