Natural stone, already millions of years old when quarried and manipulated for our own needs, would appear to be impervious to decay. It is important to treat natural stone surfaces with care using appropriate treatment methods. In the literature, there are many different methods of stone surface treatment in order to improve the aesthetic appearance of the surface of the marble slab or tile or to increase the roughness. A new concept, water jet treatment, currently used by the sector and have more popularity than traditional methods. Water jet technology enables to obtain a surface with required roughness while preserving aesthetic appearance of the stone; however, this technology overcomes some disadvantages such as low productivity and high processing costs. Water jet treatment has been investigated in terms of surface quality, and the effects of working conditions on surface quality. The aim of this study is to determine the optimum working conditions of water jet surface treatment by using statistical and geostatistical methods. Laboratory and geostatistical studies have been carried out on Sardinia basalt samples under the conditions of different work distance, pump pressure and rate of progression.
Nowadays natural stones and natural stone products are demanded more than ever. Especially surface treated products are very popular in market. In parallel this situation number of surface treatment method are growing to answer demanded variety of natural stone products.). Surface treatment is a set of operations performed on the surface, outside borders and edges of stone elements to give a certain appearance and also to provide housing for anchorage devices (Primavori, 2003). There are a number of methods of stone surface processing and finishing such as chiseling, bush hammering, sand blasting, scratching, flaming, grinding, water treatment. The choice of the method depends on the type and the conditions of the material, the aesthetic effect (pattern, roughness, chrominance, luminance and glossiness), economics of the working, tradition and also market trends (Careddu, 2006; Ciccu and Bortolussi, 2010). All these methods make each surface different by changing their aesthetic, pattern, roughness, chrominance, luminance and glossiness.
Water jetting is a relatively new process of stone surface treatment based on the action of very high velocity water jets generated at constant pressure and water jet treated stone surfaces are of higher level of aesthetical appearance than the other methods (Careddu et al., 2007; Costa, 2007; Careddu et al., 2008). This process leads a controllable and rapid surface erosion hence reterrain the surface.
