Introduction to cradle system on panel paintings.

Last week a colleague ask me if was necessary concern about wood stability during varnish removing on a 17th century Dutch panel painting with a cradle system.

I thought that was a good case to writing something and open a discussion about it.

The cradle system has been developed in the past to solve deformation problem on paintings on wood and to obtain a flat painted surface.

The system applied on the back of the panel is made of two group of elements,

one vertically glued or sometimes nailed in the direction of the wood grain, and

a second one in the horizontal direction in contrast to the first one.

The horizontal members they pass across the verticals thanks to apposite  space created in the thickness of the verticals members.

Before apply the vertical members the surface of the painting need be completely flat without irregularity to don’t compromise the adhesion of the glue.

Most of the time paintings are going to miss until half or few centimeters of  original thickness during this process.

In fact important documentations like inscriptions , tools marks and other informations related to the object are lost!!

About the paint surface the system create an intense and constant mechanical stress to the paint layers due to the rigidity of the system that doesn’t allowed higroscopic movimentation during climate fluctuation.

The result is delamination of the paint layers, micro lifting and in several cases lost.

This structure if has been applied on an object for more then 10 or 20 years can already be a problem for the wood support and for the paint layers also if applied on a panel made with one plank.

The majority of the panels that show this system is because are made by planks with  tangential or sub tangential cut.

This typology of cuts are more sensitive to deformation and higroscopic movimentation.

You will never see a cradle on a panel made  with planks with radial cut! If you see please call me.

On the picture above at the top you can see the  points that are accumulating mechanical stress and released to the paint surface.

At the bottom the detail of the cracks visible on the paint surface consequence of continuous movimentation during unstable climate parameters.

Some times the fractures are not visible from the back and even from the front, it is just manner of time .The environmental conditions are playing a crucial rule!

However some particular ground layer  composition or paint layer are more resistant , or  painting that they have a fabric on contact with the wood surface, but for sure  they will not resist forever!

The approach must  be gradual and careful on modify the system or remove it  completely .

For sure the first step to take is to release some tensions giving a little bit space to the wood support to move gradually.

This can be done replacing the horizontal members with a more flexible wood or cut the horizontal member in two pieces to make them more flexible, but of course the conditions of the paint surface need be check some time should be necessary facing part of the paint surface.

This approach is fundamental even if the varnish of the painting need be removed.

This because the varnish is an isolation layer that doesn’t allowed the humidity to be in contact with the paint surface and part of the paint layer are in place thanks to the varnish.

When the varnish is removed the paint layers and the ground layer that accumulated mechanical stress from the cradle system can failure producing new cracks.

However I want just say that all the elements of an object they are aging together but if some of this element is going to change ,modify or removed  also the others they will be affect by this change .At this point it is necessary to make a preliminary step before reach the final treatment that will preserve the object .

For more detailed informations or a particular conservation treatment to solve on panel paintings altarpieces and wood sculpture feel free to contact me.

See you at the next post!

Aldo