An investigation on the efficiency of water-jet technology for graffiti cleaning

The scope of this study is to investigate the possible usage of water-jet technology for graffiti cleaning and to find out the best operational conditions of water-jet machine as cleaner. For this goal, Carrara marble was selected as a test stone. Three samples were prepared and 12 different areas were determined on them. Then, different operational conditions of water-jet were applied into these twelve pre-painted marble surfaces. These different operational conditions involve different travel speed, water pressure or inter-distance between passes of the machine to figure out the best combination. After that, image analysis methods were used in order to evaluate the conditions and find out the best one. In addition, roughness features of the marble samples were measured, because water-jet application can cause excavation, which may affect on the stone surface. Finally, it is concluded that water-jet machine can be used for graffiti cleaning with specific operational conditions, which are selected by using both image analysis and roughness test results. As a conclusion, it can be said that if the stone is painted heavily, then travel speed of the machine must be reduced. Oppositely, if the stone is slightly painted, the best solution is to increase both the inter-distance between passes and the travel speed of the jet. Economic considerations of water-jet application are also carried out.