Technical Imaging & Analysis

Technical Imaging & Analysis

At Redivivus, we direct and conduct a comprehensive range of technical investigations on artworks. With an informed interpretation, these results can reveal features of the artist’s technique and material use. Our in-house instrumentation enables us to characterise fiber and pigment use, identify elemental composition, and use technical imaging to examine preparatory underdrawing, paint layering, and application techniques. Through professional collaborations we also provide analysis of binding media and dating of painting supports by dendrochronology and radiocarbon dating.

Clients request technical studies for a variety of reasons including improved understanding of their artwork, as part of a record when artworks are offered for sale, assessing and documenting condition, assisting in conservation treatment, and for security and authenticity.

Technical Imaging

Technical imaging uses specific wavelengths of energy to perform non-destructive analysis of an artwork. The resulting high-resolution images improve our understanding of the artwork’s condition and yields information on the artist’s techniques and materials. Sometimes hidden signatures or inscriptions are revealed, earlier compositions are uncovered, or pentimenti come to light. This type of investigation can be of great value for those interested in the study, research, and authorship of artworks.

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Technical Photography

As conservators, we use light and photographs to create detailed images that reveal important information about the paint's surface. For example, light from an oblique angle highlights the topographical features, while lighting from behind can reveal important knowledge about the craqueleur and the support.

Our techniques include: Visible light, raking light, specular light, transmitted light, Ultraviolet light induced fluorescence

Raking Light Photography of Panel Painting

MultiSpectral Imaging

Multispectral imaging captures the artwork’s surface in a number of spectral bands across the spectrum of light. The result allows us to observe similarities and differences by comparison of the spectral absorption curves. In tandem with X-Ray Fluorescence this gives the capability to identify and map pigment use across the surface. Multispectral analysis can also clarify and map other material distinctions.

Infrared Reflectography

Our high-resolution Apollo camera captures the infrared wavelengths reflecting off the surface of the painting. This records the varied transmission, absorption, and reflection of infrared radiation by the artwork’s materials. Many paints appear partially or completely transparent, while others such as black paints, absorb the infrared radiation and appear dark. This is particularly helpful to distinguish pigments, inscriptions, underdrawings, and changes in the artwork’s composition.

X-Radiography

X-radiographs record the transmission of radiation through an artwork’s materials. The variable thickness, density, and chemical composition of the materials are displayed in the x-ray image. Our system works digitally, recording high resolution images immediately. Because all layers of the painting and support are superimposed in one plane, the reading of X-ray images requires careful interpretation.

Technical Analysis

Scientific analysis methods also play an important part in the understanding, study, and dating of artworks. Our material testing capabilities allow us to characterize the pigment particles and identify the elemental and molecular composition of an artwork’s materials. Simply identifying a material is rarely sufficient to understand its significance. At Redivivus we fully integrate our knowledge of how artists worked, what materials they used, and when these materials were available.

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Radiocarbon Dating

Radiocarbon testing uses isotope ratios to establish a timeframe for the use of organic materials such as paper, wood, ivory, bone, and canvas fibers. Using the most advanced techniques, sampling can be done on a micro scale, allowing the possibility to date individual paint-layers or parts of an artwork.

Polarizing Microscopy

This technique employs a microscope with two polarising filters to characterise the features of a material. A small sample is mounted on a glass slide, dispersed in a clear medium, and analysed using transmitted light. We investigate the color, shape, size, sample homogeneity, refractive index, and other optical and morphological properties of the pigments and fibers, and their interaction with light. When these observations are matched to a database of reference materials, our experienced analyst can identify the specific pigment or fiber material in the sample.

Cross Section Stratigraphy

In this technique, a tiny sample is extracted from the edge of a painting or an area of paint loss and mounted in clear resin. After hardening, the resin block is cut and polished to expose all of the sample's constituent layers including any mix of ground, paint, and surface layers in a single plane. Cross sections can be examined and documented under a microscope in reflected light and ultraviolet fluorescence to give information about the pigments and particles included in each layer of the sample. They can also be analyzed using Scanning Electron Microscopy for elemental identification, FTIR for medium identification, and Raman microspectroscopy.

Dendrochronology

Dendrochronology is a dating method that uses the measurement of growth rings to determine the location and age of the tree from which wooden artworks are made. The measurement yields a specific tree ring sequence that can be compared against chronological records (or databases) of other trees belonging to the same species. The information derived from dendrochronological analysis can help contextualize the history of an object, contribute to understanding its cultural significance, provide data for cross-comparison with related wooden objects, and even aid in attribution.

Hirox Digital Microscope

At Redivivus we work with the HIROX digital microscope to capture high-definition, high-magnification images. The motorised system can scan the surface at high magnification, as well as recording videos, topographical information, and stack images to create a focused 3-D picture. These techniques can be performed at magnifications up to 2500X and provide detailed surface and pigment analysis.

X-Ray Fluorescence

This non-invasive method uses a focused beam of X-rays to excite the atoms that constitute the artwork and analyzes the energy emitted by the material. It provides a characteristic fingerprint of the elements contained in the small sample area, allowing us to identify the artwork’s inorganic components such as metals, pigments, and other paint ingredients. Once identified, the materials can be compared to pigments and paints available at the time and information on materials commonly used by the artist.