Objective: This study aims to compare the results of staining tests carried out on natural silicate ornamental stone samples. The staining test was applied to different regions of the same slab of rock, assessing the behavior of a staining agent, oil, in relation to the textural variations and compositional characteristics of the natural rocks investigated. From this analysis, we hope to better understand how these properties influence the interaction with the staining agent, contributing to knowledge about the durability and aesthetic maintenance of ornamental stones in commercial use.
Theoretical background: Ornamental stones, as well as being beautiful, must be durable and functional, maintaining their aesthetic, physical and chemical properties (ASTM, 2005). However, cleaning products, food and environmental factors can alter these characteristics. Aires-Barros (1991) defines this “alterability” as a function of intrinsic factors (material and porosity), extrinsic factors (environment) and time, which together determine the durability of stone.
Method/project/approach: A study compared the behavior of three types of stone exposed to oil as a staining agent, applying a stain resistance test methodology. The procedure followed Document 20 of the ABIROCHAS Technical Documents Collection on the technological characterization of cladding stones and the practices described by Castilho (2018) in Technological Characterization of Ornamental Stones: Laboratory Practices.
Results and conclusion: The study carried out in this work showed that the same slab of natural ornamental stone can have areas that are more susceptible to oil staining than other areas on the same slab. The areas with the finest crystalline texture and consequently the least expressive cracking were the areas least affected by oil staining. Another observation based on the results obtained was the loss of shine associated with the areas subjected to staining, even those where the stain was visually removed. In addition to these observations, the color of the ornamental stone, as well as the type of surface finish on the slabs, may also be important variables in the effect of oil staining, since the Anthracite stone with a black color and brushed surface finish was the lithotype that did not show stains after contact with oil.
Implications of the research: Natural ornamental stone comprises materials with textural, compositional and structural heterogeneities observed even in a single slab, so the work seeks, through comparisons, to observe areas of greater susceptibility in natural ornamental stone slabs that can interact with oil staining agents.
Originality/value: to contribute to the improvement of technologies that contribute to the best performance of natural ornamental stones, taking into account the type of resin and associated finishes.
