Valentin de Boulogne

Abraham Sacrificing Isaac
About 1630-1631
Oil on canvas
Gift of Lord Strathcona and family

The dramatically innovative works of Caravaggio were an exciting source of inspiration for the impressionable young artists arriving in Rome from France and Holland in the early seventeenth century. Among the most talented and esteemed of them was Valentin de Boulogne. Valentin spent his entire brief career in Rome, his style enriched by exposure to such contemporaries as Saraceni, Honthorst and Ribera.  His patrons included the eminent Cardinal Francesco Barberini. Abraham Sacrificing Isaac, one of Valentin’s last works, executed at the peak of his artistic powers, employs a rich Caravagesque chiaroscuro to underline the emotional intensity of this highly dramatic moment. Theologically prefiguring the sacrifice of Christ, the painting juxtaposes the passive acceptance by Isaac to his fate with the interruption of Abraham’s violent act by the descending angel.  This large-scale masterpiece on canvas entered the great seventeenth-century collection of Cardinal Ascanio Filomarino after the artist’s death. Still not quite finished in its details, it fascinatingly reveals both the artist’s working method and the evolution of the final composition.

Treatment Overview

The goal of the conservation treatment was to improve the appearance and legibility of a painting that had been damaged, altered and poorly restored many times and in so doing, to ensure its long-term preservation. An in-depth study of the work, including a detailed technical examination and scientific analysis, led to a better understanding of the artist’s intentions and working methods. An important aspect of the study was to resolve whether certain incomplete compositional elements were the result of past damage or had been left unfinished by the artist. With this knowledge, the painting was brought closer to its original state while respecting changes that had occurred over time.

Technical Examination

A preliminary study included a careful examination of the surface under strong lighting and through a microscope. The work was deemed in stable condition structurally. The old glue lining was acceptable despite the presence of overall deformations of the paint in the form of cupping and weave accentuation. Additional information was obtained from an examination under ultraviolet light and from photos taken with wavelength-specific light, the goal being to obtain a clearer understanding of the structure and condition of the painting. UV fluorescence provided information about the treatment history of the painting. Infrared and X-ray images provided insight into the artist’s creative process and revealed compositional changes. Minute paint samples from carefully selected areas were taken for cross-section analysis and pigment identification, contributing to our knowledge of the artist’s painting technique and materials.

Surface cleaning and varnish removal

Nettoyage de surface

In order to reveal the original paint surface, layers of dirt, as well as dark, often opaque varnishes and discoloured retouching, needed to be removed. Tests were performed with various cleaning agents to find the most effective and safest cleaning system.

Nettoyage de surface

Surface cleaning removed superficial soiling and permitted a subsequent, more controlled varnish removal. The varnish consisted of multiple, uneven layers of aged natural resin, partially and selectively removed in the past, and a newer layer of synthetic resin.

Nettoyage de surface

After testing the solubility of both varnish and paint layers, appropriate mixtures of organic solvents were chosen to remove the varnishes systematically, layer by layer. The most demanding steps proved to be the removal of areas of highly oxidized older varnish, tough oil-based overpaint and crudely textured fills. In some cases, these materials could only be thinned.

Filling losses

The removal of varnish and retouchings revealed the actual state of the paint surface, damaged by aggressive cleanings and altered by past restorations. Along with areas of paint loss, the surface was generally abraded, resulting in fractured brush strokes and worn-down shadows. Old fills, covering ground and paint losses were embrittled. Most were poorly textured and too visible; some were too large and covered original paint. Many paint losses had been left unfilled. In order to prepare the surface for inpainting, fills were corrected or replaced and textured. New infilling was done with a material chosen for its reversibility and stability. Attention was paid to achieve appropriate surface level. A variety of tools were used to mimic crack patterns and to create texture that imitated surrounding paint characteristics and weave imprint, the goal being a unified paint surface.



The reintegration of the paint surface involved a multi-layered approach using carefully chosen paints and resins that are easily removable and chemically stable. Initial toning of fills was done with gouache. A thin layer of a non-yellowing synthetic varnish was then brushed over the surface to protect the original paint and facilitate accurate colour matching. Final inpainting was carried out with dry pigments mixed with a synthetic resin. The poor condition of the original paint and the non finito aspect of the work required a particularly restrained and sensitive approach to inpainting. Losses were concealed and areas of abrasion selectively reduced but numerous pentimenti (compositional changes) were left apparent. The challenge was to achieve a balance between well-preserved areas of the painting, those irreversibly damaged and the ambiguous unfinished areas, restoring coherence, legibility of the image and compositional harmony.



Because of the painting’s strong surface texture and unevenly abraded paint, many thin layers of varnish were brushed and sprayed on to create a visually pleasing protective coating. For the final layers, a natural resin, traditionally applied to Old Master paintings, was chosen for its optical and aesthetic qualities such as good colour saturation and the desired degree of gloss. It was chemically stabilized to improve its aging characteristics and prevent yellowing. The painting had for a long time been housed in a historically inaccurate, aesthetically jarring frame. We were able to replace it with a copy of a seventeenth-century central Italian frame. It was constructed to our specifications and gilded in-house.

Conservation on this work was made possible by  Bank of America Merrill Lynch