Removal of Graffiti from Morelia’s Quarry Stone by High Power Diode Laser

ABSTRACTThe historical monuments such as cathedrals, public buildings and so on, are a fundamental part of artistic heritage of a country. They reflect, ultimately, much of its culture and history. For several decades, their aspect has been seriously changed by graffiti, which clearly endangers their preservation state and causes loss of their esthetic appearance and historic value. This damages seriously the self-esteem of residents who witness the continued and strong degradation of their cultural heritage. The aim of this work is to study the removal of graffiti from a characteristic stone which is used in Morelia (México) as the raw material for architectural monuments, using a high power diode laser treatment. We concluded that continuous wave regime leads to better results than modulated wave regime; additionally, a two laser passes process demonstrated a high performance.