This copy of "Portrait of Sculptor Joseph Wilton" of the original by Louis-Gabriel Blanchet was brought in for cleaning and general treatment. The painting had a discolored layer of natural resin varnish and has numerous drying cracks that were inpainted in the past. There was a stretcher crease along the top edge of the painting.
The discolored varnish was removed with a tested solvent mixture. (left side)
Along with the discolored varnish, the previous inpainting was also removed from all the areas of drying (traction) cracks. These will all have to be inpainted again.
These cracks occur when the underlying layer of paint dries at a different rate than the layer on top of it. This can be caused by painting lean over fat or with the use of Bitumen which was popular in the 18th and 19th centuries. Bitumen never forms a fully stable, cross-linked polymer. It remains permanently semi-plastic and flows or contracts under top layers, causing deep, devastating wide cracks.
Here's the finished treatment with a synthetic non-yellowing stable varnish and losses inpainted. A final spray varnish was then applied. This varnish has similar saturation and refractive qualities of the original varnish without the chemical instability of oxidizing natural resins in which ambient oxygen attacks the unsaturated bonds (double bonds between carbon atoms) and allylic positions inherent in the triterpenoid molecules. Not only does the varnish yellow, but it also becomes both brittle and degraded as well as less and less soluble in aliphatic solvents. When the conservator is required to use more polar solvents, the danger of removing original glazes and pigment increases. It is always the responsibility of the conservator to anticipate how future conservation will be affected by the use of materials.
"This Mother and Child painting was created by German born American history painter Emanuel Leutze, best known for his work Washington Crossing the Delaware. The surface was obscured by a heavy layer of grime and discolored varnish. A recent tear was also present in the upper center. The painting had a previous glue lining, which remained stable."
This image shows the halfway point of a discolored varnish removal, a process which has revealed the original skin tones. Removal of the varnish also removed in previous inpainting of an old tear repair across the whole central area. This tear repair was structurally stable as well as the lining. I have noticed that many well executed glue linings have held up well over time.
This image shows the completed treatment, which involved joining the tear, applying a synthetic conservation varnish, inpainting, and a final spray varnish. The use of a high refractive index (RI) varnish has saturated the dark tones, thereby restoring the original contrast. Unlike natural resin varnishes such as dammar, this synthetic varnish will not oxidize or yellow over time. It is also important to note that when a natural resin varnish oxidizes, it can require stronger, more polar solvents for its removal. The paint layers of some artworks are sensitive to these solvents, which can pose a significant challenge for the conservator. A variety of synthetic varnishes are available, each with distinct visual characteristics, solubility parameters, and levels of luster, allowing the conservator to match the original surface effectively.
This is a painting of Salome and Herodias from the workshop of Peter Paul Rubens. The painting had a very discolored natural resin varnish and previous retouching in several areas.
Discolored varnish and retouching is removed on the right side of painting, revealing details in the hair and bodice stomacher. Most of the background was overpainted, obscuring background details.
During treatment, research revealed another painting from the Workshop of Rubens showing the full composition of the biblical scene of Salome and Herodias holding head of St. John the Baptist from a collection in Madrid. You can see the similarity of the features in both paintings.
After applying a synthetic varnish with similar refractive characteristics of natural resin and the inpainting of previous damaged areas, details in the hair and background became even more evident along with the revelation of an obscured earring. Architectural elements are also now seen similar to the Madrid composition.
Here's a cleaning image of a coral reef painting by artist/naturalist Chris Olsen. He is known for his diorama with accompanying painting at the American Museum of Natural History in 1935.
I found it interesting to learn from the painting's owner that he painted these studies from life in an observation tube descending underwater from a boat. (pictured above).
Here's an extreme example of a half surface cleaned painting that was exposed to cigarette smoke for almost half a century. The owner remembered it being white when he purchased it. Cleaning required the use of a specially formulated chelator and a great deal of patience to safely remove the nicotine and grime layer by layer.
This painting by Hudson River School artist Robert Walter Weir was brought in to address lifting paint and surface grime.
The lifting paint was stabilized and set in plane through the application of local consolidation and hot air tool. A silicon tipped tool was used to manipulate the surface during the process.
After a series of tests, a thick layer of discolored varnish was removed using cotton swabs and an appropriate solvent. Previous retouching was also removed during this process. (left side cleaned)
A synthetic layer of non-yellowing varnish with similar visual characteristics was applied to the surface saturating the darks. Areas of previous retouching were inpainted using reversible conservation paints. A final spray coat of varnish was applied to even out the surface and act as a protective barrier.
Datum Fine Art Conservation recently completed restoration of the outdoor mural "History of Women in Northampton 1600-1980" in Northampton MA along with the Hestia Art Collective.
