Efficacy of mechanical procedures for removal of a lichen and a gypsum black crust from granite

This paper provides preliminary data on the use of three different mechanical procedures to remove lichen Diploschistes scruposus and a gypsum black crust from an ornamental granite. The methods used were wet sandblasting (Hydrogommage®), dry (IBIX®) dry-ice blasting. In addition, lichens also removed by scraping with scalpel. cleaning efficacy undesirable effects granite evaluated stereomicroscopy, colour spectrophotometry, Fourier-transform infrared spectroscopy scanning electron microscopy. depended deposit being removed: i) for lichen, ice blasting produced best results, while crust, although both particulate matter crystals remained surface; ii) method induced extraction grains subsequent appearance fissures; iii) was totally unsatisfactory iv) failed crust.