The materials and techniques used to make such a variety of paintings vary enormously. Oil paint, canvas, panel, hardboard, egg tempera, glue tempera, beeswax, natural resins, modern synthetic resins, house–paint, chocolate, gold leaf and water–colour all feature in the collection. Tates conservators are responsible for the care and treatment of these paintings.
Technical examination and analysis
Technical examination and analysis are crucial to developing our understanding of paintings.
Through microscopic and chemical analyses conservators discovered that the background in John Bettes’s painting was originally bright blue. The colour was derived from the pigment smalt, which is essentially blue glass ground up into small particles. Bound in linseed oil, however, smalt often discolours to the dark greens and browns seen in this portrait; this change of state is not reversible. Artists in John Bettes’s time would likely not have known that this would happen.
Cleaning is a particularly delicate and demanding part of conserving and restoring paintings. Layers of dirt, discoloured varnish and old restorations that may be disfiguring or obscuring parts of the composition are painstakingly removed.
The dark varnish on Thomas Gainsborough’s portrait Edward Richard Gardiner circa 1760–8 made it hard to see the wonderful silvery tones and featherlight brushwork. As the varnish was removed, the lively qualities of the paint handling in the painting began to emerge.
Similarly, with JMW Turner’s heroic landscape, The Opening of the Wallhalla, 1842 exhibited 1843, the dingy grey layer of old varnish and dirt impaired our appreciation of the painting’s subtle colours, sense of space, and fine condition.
Removing deposits of dirt from unvarnished paintings can have similar positive effects, as in Gwen John’s The Convalescent 1918–9.
Structural work might also be necessary if the canvas or wooden panels that support the paint surface need strengthening or have been damaged.
Mark Rothko’s popular painting Untitled circa 1950–2 needed treatment to remove two dents in the canvas support. Restoring the canvas and paint to its previous state was a slow and gradual process. Distilled water was misted onto the canvas reverse to soften the canvas fibres and plasticise the paint. Through gentle manipulation of the canvas from the reverse, using a specialised temperature controlled iron, the fabric was eased back into plane.
Looking after works
Some paintings can be conserved but not restored due to fundamental changes caused by, for example, the artist’s choice of method and materials.
For Editha and the Monks Searching for the Body of Harold exhibited 1834 William Hilton mixed non–drying materials into his oil paint. The result was that the top layers of paint have shrunk in relation to those underneath them, leaving wide cracks. A nineteenth–century note in the painting’s file recommends that the painting be rotated 180 degrees every six months to allow the parts of the painting to move back to their original position. Unfortunately the problem is more complex than this would suggest, and cannot be reversed.
Tate Paintings department
Technicians and administrative staff: 1
Range of activity:
- Care of Tate’s collection of paintings, recording their structure a condition, ensuring safe storage and display and performing necessary treatment
- Checking loans in for Tate exhibitions
- Carrying out research including the technical examination of artist’s technique, methods and materials
- Acquiring information from living artists through interviews and questionnaires
- Developing treatment and conservation procedures