ConNext-2021

6 Calculating Conservation? KEYWORDS: calculating tool, open air museum, educational object, traces of usage, environmental stress. The subject of this paper is the ongoing conservation-restoration of a calculating tool from the late 19 th to early 20 th century. The counting frame belongs to the Freilichtmuseum Lindlar (Lindlar Open Air Museum) in North Rhine Westphalia and came to the workshops of the CICS in 2019. The object in question consists of a standing dark wooden frame with 10 horizontal metal wires and 100 wooden balls. 50 balls are painted with a dark colour while the other 50 are painted white. The frame at first appears fairly simple in terms of construction and design. One might say it resembles a DIY project. However, detailed investigation revealed the frame, simple in structure and decoration, to be a piece of domestic craftsmanship, rather than an industrial product. Since the object is a technical instrument that is likely to have been used daily in classrooms, its surface is covered in a layer of dust and skin grease. The paint layer on the white wooden balls also shows a lot of scratches, markings and further evidence of use. The oil-bound binding media is in a particularly poor and unstable condition and is lifting from the substrate. The object shows the development and history of school education and is of sociological and cultural interest as well as of historical significance. Therefore, it should be preserved for future generations. In its museum context and in respect to the special circumstances of an open-air museum the frame should still fulfil its original purpose as an object of education. Visitors and museum staff are looking forward to using the frame occasionally which is the challenge for the preservation. The ongoing conservation-restoration process consists of stabilising the structure of the paint layer, the cleaning of all its surfaces, and planning preventive conservation measurements. Due to the vulnerability of the object and the expected mechanical and climatic stress through the museum conditions, it is important to find a good balance between too much protection and too less preservation. franziska.eber.lle[at] gmail.com