Decades of pollution removed from the National Gallery’s facade

The National Gallery’s grand stone frontage has been restored to its 1830s appearance now that decades of pollution has been cleaned off the front of the building.

Ahead of the gallery’s 200th anniversary, the external façade overlooking Trafalgar Square underwent a major phased cleaning and refurbishment programme, made possible by support from the late Julia Rausing and her husband Hans Rausing.

With the final scaffolding now removed, the stone looks as fresh and clean as it did when the young National Gallery formally opened to the public in 1838.

A slightly bigger task than the average domestic spring clean, the front of the building is clad in Portland stone – a relatively soft and porous natural material mined from Dorset. The challenge for conservation specialists Paye Stonework and Restoration was to clean the building but without removing the patina of age, while conserving as much as possible of the original elements.

All areas have been cleaned using a combination of dry cleaning, superheated water cleaning, and mild abrasive water-based cleaning techniques. Areas with stubborn and dark staining were then treated with a poultice to draw out the pollutants, followed by a final washdown to remove remaining dust or debris.

In some cases, cleaning also revealed the need for repairs in places where the façade’s watertightness was either already compromised or, if left, would have put the stone at risk of further damage. Missing stone parts were not rebuilt and replaced unless strictly necessary.

Gabriele Finaldi, Director of the National Gallery, said, “The National Gallery façade on Trafalgar Square is one of London’s most recognizable sights. Julia Rausing encouraged us to undertake the complex task of cleaning and restoring it for the Gallery’s Bicentenary year. We are enormously grateful for Julia and Hans’ support and are now immensely proud of our gleaming, elegant façade.”