Visit the Conservator

Preparations for a Journey

A work of Unique National Importance, Peter Paul Rubens The Ascent to Calvary. The Bearing of the Cross, c. 1634, is being conserved prior to returning temporarily to an exhibition in its native Belgium.

Made by one of the greatest
Perhaps the genius of any painter is most obvious in his drawings and sketches. This is certainly true of this beautiful sketch by Peter Paul Rubens (1577-1640), The Ascent to Calvary. The Bearing of the Cross from c. 1634.

The sketch is made with black chalk and brown paint on a light ground. Only in some details did Rubens add a little colour to the image. Because of the small amount of paint the sketchily drawn lines are very clearly visible - it is thrilling to see how Rubens manages to indicate forms and faces with just a few quick lines.

Rubens exhibition in Brussels
The oil sketch has to be conserved prior to a journey to Brussels for a Rubens exhibition in the Royal Museum of Fine Arts in the fall of this year.

In its present condition the painting is not fit for the journey. In several places the paint layers are being pushed away from the wooden panel, the paint is ‘tenting’ and would risk falling off if not consolidated.

The cradle on the reverse of the painting

The cradle on the reverse of the painting

The challenge in wood
The main reason for these problems is that even 375 years after the felling of the tree, the wood still reacts to climate changes in the surrounding atmosphere. Especially across the grain wooden panels can swell and shrink several millimetres. These deformations can usually be absorbed by the paint layers on a panel, as long as the changes are not too sudden and the panel is free to move in a convex or concave direction. But in the case of this oil sketch the panel is forced into a very straight position by an auxiliary support mounted on the reverse, a so called cradle.

The detail shows the thickness of the panel along the bottom edge

The detail shows the thickness of the panel along the bottom edge

From panel to 'washboard'
In order to mount a cradle on the reverse of an uneven panel it had to be smoothened down with a plane until it was even. As can be seen in the detail of the bottom edge, the original panel was planed down to not much more than 1 millimetre.

Then battens were glued to the surface following the direction of the wood grain. Cross members were inserted in openings below, but not glued to the panel. In this way the cross battens would act as wooden springs attempting to keep the panel as flat as possible. But as both the panel and the wooden battens attached to it react to environmental changes, the now very thin panel has been deformed into a ‘washboard’.

How to conserve this painting
The first step for conserving this painting is the consolidating of the tenting and flaking paint. This is done by fastening the loose paint with fish glue and flattening the tenting paint with a little heat and pressure. There is unfortunately not enough room for the tenting paint, so a little tenting will have to be accepted.

To make sure the condition of the sketch will not be at risk during the journey and the exhibition in Brussels the painting will be mounted in a microclimate frame, a sealed box within the picture frame. This ensures that the microclimate around the painting inside the box is stable. A specialist among the museum's art-handlers constructs microclimate frames for paintings.

The return of Rubens’ quick hand
With the painting in the studio the possibilities of cleaning are being examined. The varnish later applied on the oil sketch consists of several layers. Not only have these layers yellowed with time, but they are also obscured by dust in between the layers. Removing these varnish layers will bring back the drawing character of the sketch and bring us closer to Rubens’ quick hand.

Conservator Johanneke Verhave by the painting

Conservator Johanneke Verhave by the painting

Written by
Johanneke Verhave
Master of Art, Conservator of Paintings

Updated: 15.oct.2014
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