The great majority of paintings in the National Gallery’s collection are on wood or canvas. Specifying the support, the main structural layer, is the principal method of categorising the physical nature of a particular work.
In the case of The Marriage of Strongbow and Aoife, Maclise painted this iconic work on canvas and used a layer structure that is broadly similar to most easel paintings. The painting is made up of - in order from bottom to top - the support, ground, paint, and surface coating. The fabric support is attached to a stretcher and tensioned by means of wooden keys, a type of flat triangular wedge that is secured in each corner of the stretcher to adjust tension levels and create a smooth even surface to paint on. The ground, a layer of opaque paint, typically a calcium carbonate and animal glue mix, is applied to the support to provide a suitable colour and texture on which to draw or paint. The paint on top of the ground can be a very thin single layer or multiple layers composed of coloured pigments mixed with a binding medium such as linseed oil. On top of the paint, there is generally a coating of synthetic or natural resin, which is used to provide saturation and to protect the paint underneath from dirt, abrasion and moisture.
All paintings begin to change from the moment the artist finishes work on them. The effects of natural ageing, light, heat and humidity and accidental damage all take their toll.
The links to the right describe the deterioration issues with the various components that make up The Marriage of Strongbow and Aoife and the treatments undertaken by the NGI conservators to ensure the stability of the painting and it’s availability for future generations to enjoy.