2012 Theses Master's

Laser cleaning of Polychrome Alabaster

Lorenzon, Marta

This research aims at analyzing the effect of laser cleaning on polychrome alabaster surfaces. As cleaning is an integral part in the conservation process, laser cleaning has been used with satisfying results in stone conservation to remove encrustation. Alongside to the aesthetically pleasing results, it is relevant to determine that laser cleaning does not have any adverse effects. Compared to the more traditional techniques, laser cleaning has many additional advantages: The diameter of the laser beam can be regulated so that areas of different dimensions can be treated. There is no physical contact between the object to be cleaned and the laser equipment. This aspect can be really relevant in treating fragile materials. Laser can be a selective tool: it can be regulated to remove dirt, without affecting the original material underneath. Lasers are effective in removing pollution encrustation from stone objects and have been used in conservation since the 1970s. Particularly the aim of this project is to determine whether laser cleaning is a suitable cleaning technique for materials like polychrome alabaster. For painted materials, laser cleaning can be an effective technique but it requires an in-depth study of the laser photochemical and photomechanical effects to avoid irreversible damage of the painted layers. If the outcome of this study is positive, laser cleaning can be added to the range of techniques used for cleaning polychrome artifacts, archaeological structures and historic buildings made of alabaster.