The Work of Conservation and Restoration

[This note is based on the Conservation Report prepared by Elline von Monschaw who, over two years from 1998 to 2000, carried out the work of conserving and restoring the painting under the guidance of Dr. Andrew O’Connor of the National Gallery.]

The painting was damaged by a fire in its vicinity. The paint layer had severe blistering lifting it off the canvas. Some paint had been lost where blisters did not survive the expansion caused by the heat of the fire. The surface layer incorporated dirt and soot from the fire and the canvas was torn in three places. The dark photograph shows a part of the blistered surface before treatment.

The repair of the tears in the canvas is a relatively standard process. The conservation work to the blistered areas was an unusual task. The paint layer required to be consolidated back to the canvas and its priming layer. Each of the blisters had to be treated individually. This was done by injecting an adhesive into each blister and then warming the surface slowly. Then, using the right amount of pressure, the paint was adjusted back into its former position. This adjustment had quite often to be done repeatedly to ensure the surface topography of the original brush strokes was maintained. A special hot air pen was used, which releases a precise temperature-controlled beam of heat onto the area of a single blister.

This work was part of Elline’s thesis for a Master in Conservation of Fine Art degree. Her thesis was based on research into fire damaged paintings. Working on our painting confirmed her observations on the differences in the blistering of the paint layer of a fire damaged painting. Firstly, the big blisters occur mainly in dark areas and thinly painted areas. This is probably connected with the pigment used, its chemical composition and its reaction to heat. These layers are extremely brittle - as in our painting.

Secondly, the thickness of the paint influences the kind of blister. Generally, thick paint layers or several layers on top of each other trap air within the layers. This causes problems for the conservator when it comes to flattening the blister. The conservator has to try and conserve the paintwork while at the same time making sure not to remodel the paint or change the painter’s intention – as seen in the flesh tones of Jesus and some of the faces.

	Loss of paint had occurred where blisters did not survive the pressure of expansion during the fire and some did not survive the transport and storage of the painting before conservation began. These areas can be seen as white blobs in the photographs.
The edges of these areas of paint loss were consolidated and then the whole surface of the painting was cleaned and excess adhesive removed. Paint losses have been made good by in-painting in an integrative way with reversible paint in order to reduce the negative optical impact. A thin coat of ‘dammar’ varnish was applied to protect the painting and to give it a saturated surface gloss.

The conservation treatment stretched over a long time span due to the nature of the damage and the slow detailed conservation process involved. Material was also collected for further research into the treatment of this rather uncommon and specialised type of damage.

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