The HART report 2002 - 2005

Historically accurate reconstructions of paint and painting composites

The HART (Historically Accurate Reconstructions Techniques) project concentrates on identifying historic recipes for artists’ oils, grounds and selected pigments, sourcing contemporary materials which are consistent with those used in the past, then preparing artists’oil painting materials according to representative historic recipes.

The reconstructions which result are used for many purposes: to evaluate historical recipes and their accuracy, to establish studio practices associated with specific materials, and to provide reference materials and standards for instrumental analysis and visual analyses.

As references, reconstructions can be compared visually with actual paint surfaces, to observe gross physical effects (e.g. the effect of adding starch to Lake Pigment), or to compare microscopic crosssections from both reconstructions and actual paintings.

Oil painting cross sections can tell us a great deal about the materials and application methods used by the artist. Interpretation has been largely based on comparison with samples from other paintings in combination with analyses of the materials present.

The Hart project has been preparing historically accurate paints and paint composites to assist this interpretation.

For example, a study of Van Gogh’s grounds is underway using this technique. Previous SEM-EDX investigations (Shell/ICN) have provided a comprehensive list of ingredients present in a range of Van Gogh’s grounds. However it has been difficult to evaluate the characteristics and proportion of these ingredients present. Therefore a series of paints were prepared with lead white and various sources of two of the common extenders identified: barium sulphate and chalk. Stepped proportions (5%, 10%, 15%, 25%, 50%, 75%) were added to lead white and cross sections have been investigated (using SEM-EDX with Kees Mensch and Ralph Haswell at the Shell Research Laboratory). Comparison with an EDX quantification programme analysing both the reconstructions and the Van Gogh samples has been initiated.

The HART Project has also been involved with an evaluation of the difference between modern and traditionally manufactured lead white pigment. The traditional material typically exhibits a broad range of particle sizes, from large chunks (10-25 μm) to tiny individual particles (0.1 μm). Whether this resulted from a deliberate mixture of different particle sizes, or is intrinsic to the material was unclear. Reconstructions convincingly demonstrate the answer.

The HART report describes how and why the recipes were reconstructed and the first results.
For more information regarding the HART report please contact Dr. Leslie A. Carlyle (e-mail: leslie.carlyle@tate.org.uk, tel.: +44 613 998 3721, UK).