Introduction 1 3 4 5 6 7 8 9 11 12 13 14 17 8 In this work we evaluate the use of a mobile fibre-optic-based Raman instrument to perform investigations in a museum context. Different types of artefacts were investigated in a variety of locations, testing and demonstrating the flexibility in instrumental set-up. In particular the experimental conditions during the examination of a virginals on exhibition were challenging. Instrument stability after travelling overseas (between Belgium and Edinburgh, UK) was also thoroughly evaluated. Experimental 19 8 18 Results and discussion 1 Table 1 Overview of the different artefacts that were investigated in this work and the analytical challenges they represent Investigated artefact Analytical challenge Egyptian sarcophagus (NMS) (A.1907.569A) Pigment identification through a thick varnish layer Egyptian sarcophagus (Glasgow) (1895.167.a) Pigment analysis with strong interference from sunlight. Transport to a different museum, analyse, and return in 1 day Dean panel (H.KL 72) Analysis of a varnished painting Kalighat painting (A.1912.122) Analysis of work on paper Indian textile banner (K.2005.234) Analysis of a textile artefact of large dimensions with a thin and friable painted decoration Mar virginals (H.LT 122) Investigation in the exhibition gallery open to the public The examination of Egyptian sarcophagi, both in the National Museums of Scotland (Edinburgh) and in the Burrell Collection (Glasgow Museums & Art Gallery) illustrate the comparative ease of transportation of the instrument. The capability of the technique to analyse pigments on artefacts covered by a thick varnish layer as well as to undertake the investigation with interference from sunlight are shown. During the examination of a Renaissance painted panel (one of the panels from Dean house, Edinburgh), strong inteference from a fluorescing varnish layer was also encountered. The possibilities of the technique for the non-invasive investigation of fragile artefacts on paper are illustrated by the yellow pigment identification on Indian Kalighat paintings and on a painted textile banner. During the latter survey the articulating arm was used to allow analysis of a large artefact displayed horizontally. Finally, working in the galleries represented an interesting experience as it involved undertaking analytical research whilst taking into account ambient conditions and visitors’ curiosity. This approach is illustrated by the study of the Mar virginals. Pigment analysis of antique Egyptian sarcophagi B C 1 19 Fig. 1 a b 2 3  1 2 3 2 3 3 19 19 2 B C 2 3 2 2 3 n 2 Fig. 2 a b  Pigment investigation of a painted panel from Dean House, Edinburgh 20 3 4 2 3 3 2 2 4 Identification of the yellow pigment from an Indian Kalighat painting 3 4 Fig. 3 4  Analysis of a painted banner 4 Fig. 4 a b c 3 4 d  4 4 3 4 4 3 3 2 3 2 2 Investigation of an early keyboard instrument, the Mar virginals A D This artefact had to be analysed while on display in the museum gallery, which enabled us to evaluate the feasibility of undertaking the analytical work in a public space. It was necessary to ensure that there were no health and safety risks, especially from direct or scattered light from the laser beam, as well as keeping the electronics and power supply cables and units away from enquiring fingers. The visiting public were clearly intrigued with what was going on and to help explain this, a poster informed the visitors about the experiments. 8 5 Fig. 5 Experimental set-up for the investigation of the Mar virginals  3 2 −1 −1 −1 2 3 3 2 9 Conclusions This work reports on the application of mobile Raman spectroscopy to the non-invasive investigation of a range of object of arts in a museum context. The different cases presented here illustrate different obstacles and analytical challenges that are often encountered during direct Raman investigations of museum objects. The investigation of two antique Egyptian sarcophagi shows the possibilities of the technique to deal with artefacts covered by a thick varnish layer as well as the investigation with the interference of ambient sunlight in the conservation laboratory. The investigation of the Dean House panel illustrates the possibilities of pigment investigation although a fluorescing varnish layer is present; the suitability of the method to analyse fragile artefacts was demonstrated by the investigation of Indian Kalighat paintings on paper; the textile banner was both fragile and large. Finally, the Mar virginals has been examined for the first time directly in the exhibition gallery with normal lighting conditions and with visitors present. All these examples illustrate that non-destructive, mobile Raman spectroscopy is able to cover a broad field of research questions on artistic and historical objects, in a range of different experimental conditions, encountered in a museum context.