LITMIR.BIZ

      Figure 5: 3D images representing the Carrara marble sample before and after cleaning by micro-sandblasting and its corresponding graph of surface roughness before and after cleaning. The red line shows the measurement line.

       Conclusions

      The analysis with 3D Optical microscopy profilometer has highlighted quantitatively how a routine mild cleaned can alter the surface of a stone material.

      The analyses have highlighted that in an abrasion-resistant material such as marble the effect of the impact of the grains of sand on the surface varies in relation to the angle of impact of the single grain, which in turn affects the roughness of the material by altering its surface polishing.

      In this research, three materials of different hardness and abrasion resistance were analysed, and in fact it was observed that according to the morphology of the samples, the alterations generated by the treatment increase the roughness and in the case of the samples that were not very resistant to abrasion, such as the Noto Calcarenite Lime stone, also involved significant loss of material compromising its macroscopic appearance.

      In an abrasion-resistant material, such as Serena stone, which apparently does not show any alteration of the surface visible to the naked eye, an increase in roughness is observed microscopically which increases the surface absorption.

      This new technique is applicable as an alternative and/or in addition to optical color measurements during laboratory tests and complementary to investigations such as SEM (Schroettner et al. 2006).

      274As a future perspective of the research, the possibility of creating an algorithm for the evaluation of surface porosity variations is being evaluated by comparing the data obtained with Alicona, mercury porosiment and micro-CT.

       References

      ASTM C1515 – 2014 Standard Guide for Cleaning of Exterior Dimension Stone, Vertical and Horizontal Surfaces, New or Existing.

      ASTM E1857−97 (Reapproved 2013) Standard Guide forSelection of Cleaning Techniques for Masonry, Concrete, and Stucco Surfaces.

      Avagliano R., Guidetto V., Martini G., Randone E., Riccardi M. P. 2013. Artwork analisis by optical surface profilometry. Conference 8790: Optics for Arts, Architecture, and Archaeology IV 15–16 May 2013 Proc. of SPIE Vol. 8790, pp. 1–4.

      BS8221-1:2012. Code of practice for cleaning and surface repair of buildings – Part 1: Cleaning of natural stone, brick, terracotta and concrete

      Carvalhão M., Dionísio A. 2015. Evaluation of mechanical soft-abrasive blasting and chemical cleaning methods on alkyd-paint graffiti made on calcareous stones. J. Cult. Herit., Volume 16, pp 579–590.

      Doehne, E. F., Price, C. A. 2011. Stone conservation: An Overview of Current Research; The Getty Conservation Institute: Los Angeles, CA, USA.

      Demoulin, T., Girardet, F., Wangler, T. P.; Scherer, G. W., Flatt, R. J. 2016. On-site monitoring for better selection of stone repairs: A case study. Herit. Sci. 4, 38.

      Gulotta, D., Toniolo, L. 2019. Conservation of the Built Heritage: Pilot Site, Approach to Design a Sustainable Process, J. Heritage, 2, 797–812; doi:10.3390/heritage2010052.

      ICOMOS. 2008. Illustrated Glossary on Stone Deterioration Patterns; International Council on Monuments and Sites: Paris, France.

      Mecchi A. M., Poli T., Realini M., Sansonetti A. 2008. A proposal for common approach in chosing tests for the protocol evaluation of cleaning methods. In proceedings 11th international congress on deterioration and conservation of stone, volume 1, pp 425–432.

      Perez-Monserrat, E. M., Varas, M. J., Fort, R.; de Buergo, M. A. 2011. Assessment of different methods for cleaning the limestone façades of the former Workers Hospital of Madrid, Spain. Stud. Conserv, 56, 298–313.

      Pozo-Antonio J. S., Ramil A., Rivas T., López A. J., Fiorucci M. P. 2016. Effectiveness of chemical, mechanical and laser cleaning methods of sulphated black crusts developed on granite, Construction and Building Materials 112 682–69.

      Pozo-Antonio J. S., Rivas T., López A. J., Fiorucci M. P., Ramil A., 2016, Effectiveness of granite cleaning procedures in cultural heritage: A Review. Sci. Total Environ., Volume 57, pp 1017–1028.

      Revez, M. J.; Delgado Rodrigues, J. 2016. Incompatibility risk assessment procedure for the cleaning of built heritage. J. Cult. Herit. 18, 219–228.

      Schroettner H., Schmied M., Schere S. 2006. Comparison of 3D Surface Reconstruction Data from Certified Depth Standards Obtained by SEM and an Infinite Focus Measurement Machine (IFM). Microchim Acta, Volume 155, Issue 1–2, pp 279–284.

      Turk, J., Mauko Pranjić, A., Hursthouse, A., Turner, R., Hughes, J. J. 2018. Decision support criteria and the development of a decision support tool for the selection of conservation materials for the built cultural heritage. J. Cult. Herit.

      UNI EN 14157:2017. Natural stone test methods – Determination of the abrasion resistance.