Technical Services
Technical imaging and scientific analysis of paintings

Technical analysis can help determine the materials used by an artist in order to study the genesis of a work and the artist’s painting technique. This can inform both the restoration and conservation of a painting, and may also help with attribution and dating.

Alongside written documentation, digital photography is used to illustrate and record information about the condition and stages of treatment throughout the restoration process. The Studio’s standard digital photography includes imaging paintings under ‘normal’ lighting conditions, as well as in a ‘raking’ light, and under ultraviolet and infrared radiation.

In addition to the digital photography and photomicrography carried out by the Studio, other technical analysis such as medium and pigment analysis is commissioned from outside specialists.

Digital Photomicrography

Photomicrography describes photographs taken down a stereomicroscope at high magnification. These images are used to view and record information about the artist's materials and painting technique, to photograph inscriptions, and to document the painting’s condition.

The Studio uses a Nikon stereoscopic microscope for examination as well as photomicrography. Images are taken using a digital camera head and the Nikon NIS-Elements imaging software.

Ultraviolet Fluorescence Photography

Certain organic materials, including natural resin varnishes and some pigments, luminesce under ultraviolet light. Photography taken under ultraviolet illumination is therefore used to record information about the artist's use of medium, pigments and varnish, in addition to recording areas of retouching.

The Studio uses ultraviolet fluorescence photography at various stages throughout the restoration treatment in order to monitor and record the progress of work. Photographs are captured using a digital camera with a band-pass filter for ultraviolet and visible light.

Digital Infrared Photography

Infrared radiation penetrates below the surface of a painting, and so can record information beyond that which is visible to the naked eye. Digital infrared photography captures images over a narrow range within the electromagnetic spectrum.

Both digital infrared photography and transmitted infrared photography are used as investigative tools in the Studio. The former can reveal information beneath the upper paint layers about preparatory drawings (‘underdrawings’) and the genesis of the work, whilst the latter may provide information regarding inscriptions and stamps on the reverse of a lined canvas.

The Studio photographs using a DSLR camera modified for use in ultraviolet, visible light and infrared, using a long-pass filter sensitive in the near-infrared range between 830nm-1050nm.

Infrared Reflectography

Infrared reflectography records a broader range of the electromagnetic spectrum, roughly between 900nm-1800nm, and so is more effective at penetrating through certain paint films. Infrared reflectography can be helpful in the further study of underdrawing, can provide information regarding the artist’s painting process, and consequently may help with problems of attribution.

This high resolution multispectral scanning can be undertaken by a trusted outside specialist, Art Discovery.

X-radiography

X-radiographs are helpful in revealing original changes which may have occurred during the development of the painting, in addition to revealing losses to the original, and information about the nature of the support. Study of X-radiographs can also provide information about artists' technique and may help to resolve problems of attribution.

X-radiography on paintings in the Studio is carried out by Art Discovery or The Courtauld Institute of Art Department of Conservation and Technology.

Dendrochronology

Dendrochronological analysis can help to date a panel by identifying the pattern of tree rings within a board to determine the geographical origin of the tree and the calendar period during which the tree grew.

Dendrochronology is carried out in the Studio, and reports prepared, by specialist Ian Tyers, Dendrochronological Consultancy Ltd.

Pigment and Medium Analysis

Cross sections and small samples for pigment and medium analysis can be taken in the Studio to answer specific questions about materials and techniques. The information gained can also help in characterising the layer structure of a painting and with resolving questions of attribution.

Paint samples are examined, analysed and interpreted by Libby Sheldon: Painting Analysis & Research or by Art Discovery.