Glass crystal models arrived in Portugal around the late 19th century, when high schools, universities, and polytechnics were gradually provided with teaching collections to support science education. Therefore, they are an important material evidence of teaching methodologies of mineral and geology science in the 20th century. The Passos Manuel high school in Lisbon, owns a significant collection of scientific heritage, currently on a long-term loan at the National Museum of Natural History and Science and the University of Lisbon, which includes a set of 98 glass crystal models. Besides glass, these models are composed by adhesives, paper, cardboard, textile threads, paper/textile adhesive tapes, and metal nuts and screws. Also, they show several levels of intervention and different conservation states. In this paper, the first results of a multi-analytic approach to chemically characterize these objects material composition will be presented. Characterization was done based on portable equipment (pXRF), or by collecting small samples further analyzed using optical microscopy and FTIR-ATR techniques. This study allowed for a first distinction between original materials from the old repairs; to develop a more accurate assessment of the conservation condition; and finally, as one of the main aims of this work, to determine preventive conservation measures in order to better preserve these cultural objects.
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