The high-pressure hot water variant works in exactly the same way as the manual method with a chemical agent for graffiti removal. The solution or paste is first applied to the unwanted artwork and then removed with a high-pressure jet. The high-pressure jet has a pressure of about 120 bar. The water temperature is around 70 degrees. The advantage of the method is the thoroughness with which the graffito itself is flushed out of the pores. However, the method can by no means be described as gentle. On the one hand, the substrate can be damaged, on the other hand, the environment is considerably polluted by this technique. This refers both to the substances that can penetrate the groundwater and to the enormous water consumption that is necessary in this process. Therefore, according to current legislation, a costly collection of the polluted water is always necessary, which makes the process considerably more expensive.
If the application of the process is incorrect, for example on a clinker facade, the salts in the soaked stones can reach the surface and white deposits can form. Once this condition has been caused, it can take up to four years until the salts have settled again and professional cleaning can be carried out.