Occasionally, sandblasting is not the right way forward...
for example the building below had several hundred stone windowsills that were stained.
For jobs such as this, pressure washing can provide the solution. A pressure washer (or power washer) is a high-pressure mechanical sprayer which can create a jet of water powerful enough to effectively remove dirt and grime, dust, mud, loose paint or mould from surfaces such as paintwork, concrete, stone, brickwork, patios and decking.
As with sandblasting, the pressure can be adjusted to suit the job and different nozzles can be used to suit the application. For more stubborn stains, hot water can be used and, if necessary, detergent as well.
High pressure water alone was enough to clean these stone windowsills all back to 'as new'. We didn't need any chemicals and there was very little clearing up required.