https://www.kentridge.studio/projects/triumphs-and-laments/

The plastic stencil was placed against the wall – suspended from the parapet at the top of the wall and pressed against the wall by people on ladders holding large brooms. Water from the river was pumped out, heated up and sprayed at pressure onto the stone and around the stencil, cleaning off the bacteria and pollution. The temperature, the pressure, the type of nozzle all controlled by the monuments commission and river authorities. Nothing was added to the wall. This was done in the knowledge that over a few years the images would fade away. The wall would darken again, through natural ageing, pollutants, graffiti; leaving a ghost of an image and a fading memory.