DOFF system can be used to wash surfaces such as brick, stone, concrete, tiles (glazed and encaustic), wood, faience and terracotta.The pressure on the surface that's being cleaned is quite gentle and the amount of the water is low even although the temperature in the device is high. Dirt or soiling usually takes many forms: pollutants from industrial or traffic emissions, grime or biological soiling by algae, fungi, bacteria and lichen. It might be that the soiling causes stone deterioration or reduces the permeability of the substrate or it may simply have a detrimental influence on the look of the buildings.