![]() |
Bulletin 2 (I:2), December 1963 |
Home |
From the Laboratory of the National
Gallery Le Pont de Narni By Corot This painting was acquired by the National Gallery in 1940. No
previously recorded technical history was available, though it was
fairly obvious from a cursory examination of its condition that it
had been restored before, at least once, between the estimated date
of execution (c. 1826-27) and the date of its accession by
the National Gallery. Superficial examination had led one to
believe that the overall yellowish tone was not of Corot's doing
but was more likely that of discoloured varnish. The opportunity to
examine this painting for possible restoration and conservation
treatment confirmed this. Examination of Figs. 1, 3, and 4, shows
the presence of the 'masking yellowed varnish'. In addition, the
disfiguring crack formation on the left side of the canvas (Fig. 2 -
as seen by raking light), could now be properly assessed in terms
of the cleaned picture, once freed of restorations and over-painting. The cleaned back of the canvas was locally reinforced with strips of wet-strength paper teased at edges using LePage's Bond-Fast glue (a type of polyvinyl acetate emulsion adhesive) in the regions of tears, holes, etc. Following this the entire back was impregnated with a wax-resin composition using an electric hand iron with thermostatic control. The composition of this adhesive was: beeswax 75%, damar resin (Singapore) 20%, and gum elemi 5%, melting range approximately 60 to 70 degrees centigrade. After impregnation the painting was turned face up and the facing paper and beeswax adhesive were removed by application of a low boiling hydrocarbon (petroleum benzine) solvent. At this time the paper supporting strips (Dutch method) were removed. The relining, or reinforcing canvas selected was cotton of smooth
texture and weave, similar to that of the original, having 27
horizontal threads and 31 vertical, double woven in both directions.
The relining canvas was placed on an expandable temporary stretcher,
and was pre-shrunk with water, and when dried, restretched. It was
then impregnated with the same composition of wax-resin adhesive as
noted above, employing the heated surface of a thermostatically
controlled hot table. The relining process was then carried out on
the same hot table using a rubber latex sheet with vacuum pressure
to bind the new canvas to the original while the correct degree of
heating was applied to distribute the wax-resin adhesive into and
through the surfaces to be bonded together. The duration of the
warming - infusing - cooling cycle was approximately 2 hours, the
temperature ranging upwards to 60 degrees, and the applied pressure
(at the edges of the rubber latex enclosure) between 1/2 and 2/3 of
an atmosphere. Descriptions of the hot table vacuum relining
technique have been reported elsewhere. (8, 9, 10) The relined,
cooled painting was restretched on a new 4-member stretcher frame
with tite-joint fasteners and metal dowels installed in the mitred
corners. This differed from the type known as the LeBron stretcher
in that only part of the tite-joint fastener was used. (11) Thus
instead of using the normal retaining ring of the tite-joint
fastener a 1/4" hanger bolt was used, allowing for more
positive tightening and loosening of the corners of the stretcher
than was formerly possible. Following this the excess film of
wax-resin on the surface of the painting was removed with petroleum
benzine solvent.
Next Page | The Virgin Child Annual Index | Author & Subject | Credits | Contact This digital collection
was produced under contract to Canada's Digital Collections program,
Industry Canada. |