Restorative Techniques was specified to carry out the specialist stone cleaning to the iconic spire of St. Brides church in Fleet Street.

The church was heavily bombed during the Second World War, although the iconic spire largely survived. It was, however, suffering from very heavy sulphation (in excess of 25mm), and SMB was contracted to undertake the removal of this.

Restorative Techniques’ initial approach was to carry out timed nebulous spraying techniques to soften the soiling prior to using the Therma Tech and Vortech systems. It became apparent quite quickly that the internal sulphation had an insoluble resin like property, unlike the external soiling which responded to the nebulous method. The company were able to remove the majority of the soiling using hand tools, followed by the super heated steam to remove any underlying soluble soiling.

The Vortech system was adopted for the removal of the final layers in conjunction with Aluminium Silicate 250 media. Working with three units simultaneously within the confines of the spire was a challenge, with each cleaner needing to adjust their own pressure and media flow rate to suit the changing tenacity of the soiling encountered.

By adapting the processes to the needs of the building, Restorative Techniques were able to make up lost ground and efficiently remove the sulphation whilst avoiding over-saturation of the stone work, thereby preventing rust staining. As a result, the original surface of the stone was once again revealed with the patina and masons tooling marks still intact.