ED TURNER, LONDON BOROUGH OF MERTON
WIMBLEDON STATION
For more than 150 years, the striking Portland stone façade of Wimbledon Station in South West London had been gradually blackened by soot - from both steam and diesel engines. Layers of everyday city grime had also taken their toll. More recently, the stonework had been defaced by graffiti.
After Merton Council awarded us the contract to return the façade to its former glory, we were faced with a number of challenges. The station is open 24 hours a day and is one of the busiest in the south-east of England, so we had to carry out almost all the work at night to avoid disruption to commuters.
More significantly, the work took place above the large glass canopy which stretches over the entrance to the station. We erected a safety cable across the front of the building and all our men, wearing full safety harnesses, were attached to it at all times. There was also a tight deadline - to complete the job before the start of the Wimbledon Tennis Championships.
A multi-stage process
The first step was to pressure wash all surfaces using clean hot water at 2800psi. We then applied a sodium hydroxide-based gel to break down dirt, grime, soot and any paint or graffiti. This was removed by hot water pressure washing, and the process was repeated a number of times over a two-week period. Stubborn areas of graffiti were given a poultice of sodium hydroxide paste which drew out the paint and ink from the pores of the stonework. All surfaces were then coated with hydroxyl acetic acid to neutralise the sodium hydroxide and complete the cleaning process.
Finally the entire façade was pressure washed twice with very hot water to remove all traces of dirt and chemicals. The results were spectacular.
