Restoration experts at the National Gallery combine a knowledge of art and science to keep paintings accessible.

An exhibition by the Conservation Department of the National Gallery of Ireland puts the painstaking and detailed work of their restorers and conservators on display.  

These dedicated professionals whose workspace is more akin to a laboratory than a gallery use photography, physics, chemistry and microbiology as well as their knowledge of art history. Repairs to paintings in the collection are carried out to conserve them for the benefit of scholars, art loves, the public and for future generations.  

The restorer must be much more than a craftsman and an art historian. He or she must be something of a scientist.

When an oil painting is selected for restoration, it is also an opportunity to verify its authenticity, as Andrew O'Connor explains taking an x-ray is a means of getting underneath the surface of the painting, 

You the layers were built up...or indeed if the picture might be a fake.

Photographs document each stage of the restoration, showing how decades of dirt are removed so that the restorer can begin the meticulous work of re-touching the painting, occasionally removing work carried out by their predecessors, 

In the case of a sixteenth century painting, it was seen fit to remove the cover-up of a prudish Victorian restorer.

Oil paintings on panels require different types of restoration techniques, as assistant restorer of oils Susan Janus demonstrates. An early sixteenth century painting which is covered in barely perceptible cracks and lines is brought back to its near original state by applying thin layers of special glue, conservation paper and then a gentle heat,  

The combination of the two will make the whole paint layer become smooth again.

Mairead McParland who is Chief Restorer of paintings, prints and drawings on paper is in the process of treating prints which have been attacked by mould in a fumigation chamber. She will then remove small yellow or brown spots known as foxing from the paper, before re-mounting the print on conservation-quality board. 

All paper which arrives into her workroom is also tested for acidity on a pH meter, as a high level of acidity indicates that an item requires treatment to prevent it from becoming brittle and discoloured. 

Another artist whose work has been restored is Harry Clarke, best known for his stained glass windows, but who was also an illustrator and painter.  

His 'Winged Angels in Profile’ paintings had suffered much damage, but have been remounted and relined, and small holes in them have filled in with cellulose fibre.

Some parts of the painting have been retouched, but large parts have not been filled in. This leads to the question of how a restorer decides that any further work on a painting might begin to interfere with the artist's original intention.  

It’s a very difficult decision to arrive at says Mairead McParland, as each work of art has its own unique attributes and issues. No restorer wants to cause damage, so  

All you can hope to do is in fact to conserve it, to prolong its life and to hope that in ten or twenty years’ time somebody will come up with the perfect answer.

This report for ‘Eureka’ was broadcast on 24 February 1976. The reporter is Caroline Erskine.