Conserving John Campbell
In the Conservation Department we’ve been working hard to get all the works ready for display in the new Portrait Gallery. My colleagues have written two blogs about our projects; the first is by Alexandra Gent:
While the Portrait Gallery is closed hundreds of objects for the new displays have been passing through the Conservation Department. I am a Paintings Conservator and have been working with the Conservation Technicians to make sure the paintings are secure in their frames and looking their best. Most of the paintings only need minimal treatment such as removing surface dirt and securing stretcher keys. But I’ve also had the chance to undertake some longer treatments and look at a few artworks more closely.
One painting that I have treated is a splendid depiction of John Campbell, 3rd Earl of Breadalbane as a child in Highland dress by the artist Charles Jervas. The varnish layer that covered this painting had become yellowed with age. When a varnish layer is discoloured the true colours and textures of the painting can be obscured and it can appear quite flat.
To make sure a painting can be cleaned safely small test areas are always cleaned first. When I removed small areas of varnish from John Campbell the little windows gave me an indication of the transformation that would happen.
Once I had found a safe solvent for removing the varnish I was able to start cleaning larger areas. This revealed distant mountains against a pale blue sky. It was very rewarding to see such a transformation.
The painting is in excellent condition and once the varnish had been removed hardly any restoration was needed.
While treating the painting I also wanted to find out more about how the artist had made it. I removed a few small, pinhead sized paint samples from near the edges. Even very small samples can provide a huge amount of information about a painting. The samples were set in resin and sanded to reveal a cross-section of the paint layers. The layers of paint are so thin that they can only be seen using a microscope. By examining the samples microscopically I was able to see that the artist had prepared the canvas by painting a thick pinkish layer over the whole surface.
I was also able to further analyse two of the paint samples with the help of Conservation Scientist Susanna Kirk from the National Museums of Scotland and my fellow NGS Paintings Conservator Lesley Stevenson. Using a scanning electron microscope and energy dispersive spectrometry (SEM-EDS) we were able to identify two different blue pigments, smalt and azurite. The very large dark, angular particle is smalt which is a pigment made from coloured glass that has been ground to make a powdered pigment.
John Campbell, 3rd Earl of Breadalbane as a child in Highland dress by Charles Jervas is now on show in Portrait of the Nation at the National Gallery Complex until 4th September 2011.