Please cite this article in press as: D. Ciofini, et al., Conservation of ethnographic artefacts: Selective laser ablation of deposits from doum palm fibers, Journal of Cultural Heritage (2017), http://dx.doi.org/10.1016/j.culher.2017.02.012 ARTICLE IN PRESS G Model CULHER-3202; No. of Pages 10 Journal of Cultural Heritage xxx (2017) xxx–xxx Available online at ScienceDirect www.sciencedirect.com Original article Conservation of ethnographic artefacts: Selective laser ablation of deposits from doum palm fibers Daniele Ciofini a , Ahmed Bedeir b , Iacopo Osticioli a , Abdelrazek Elnaggar c , Salvatore Siano a,∗ a Istituto di Fisica Applicata “N. Carrara”, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Florence, Italy b Conservation Department, Faculty of Archaeology, South Valley University, Qena , Luxor, Egypt c Conservation Department, Faculty of Archaeology, Fayoum University, Al-Fayoum, Egypt a r t i c l e i n f o Article history: Received 11 December 2016 Accepted 22 February 2017 Available online xxx Keywords: Laser cleaning Fluorescence spectroscopy Raman spectroscopy Photobleaching Vegetable fibers Lignin a b s t r a c t This work approaches the challenging cleaning problem of fragile ancient ethnographic artefact crafted using lignocellulosic fibers, which undergo different and concomitant degrading reactions (oxidation, hydrolysis, depolymerization) over time. Here, the fundamental wavelength and second harmonic of Q-Switched Nd:YAG laser were comparatively tested for the removal of deposits from woven-fibers ‘angarêb, which is exhibited at the Africa Hall of the National Geographic Society Museum (Cairo, Egypt). After a careful fiber identification, laser-induced effects were assessed on ‘angarêb fibers and fresh, nat- urally and artificially aged doum palm (Hyphanae Thebaica) reference samples by means of stratigraphic examination, UV-induced Vis fluorescence emission, Raman spectroscopy, ESEM-EDX analysis and opti- cal microscopy. Irradiation at 532 nm affected the color appearance and structural integrity of the fibers. Bond-breaking/depolymerization and bleaching occured at this wavelength, due to the significant absorp- tion of lignin/phenolic-carbohydrate and lignin-quinonoid complexes. In contrast, laser irradiation at 1064 nm did not induce any detectable discoloration or structural alteration, either in the short- or long- term diagnostic assessments. The results achieved highlight the possibility of using the latter wavelength for recovering the original surface of soiled ethnographic artefacts made of fragile vegetable fibers, which are otherwise untreatable. © 2017 Elsevier Masson SAS. All rights reserved. 1. Research aim The maintenance of artefacts crafted using vegetable fibers rep- resents a very difficult task because of the serious deterioration phenomena they typically present. Besides the need of controlled exhibition conditions, the main conservation aspect concerns the removal of soot accumulated through the fibers, whose brittleness makes very armful any chemical or mechanical action. Exogenous materials incorporated during the use of the objects, their storage or museum exhibition affect the legibility of the manufacturing details and accelerate the deterioration processes. Here, we aimed at thor- oughly investigating the laser ablation approach for safe contactless cleaning of such a class of ethnographic artefacts. The potential of the laser approach was explored for the first time on samples of a typical Sudanese bed (‘angarêb) of 19th century after identifying its constituting fibers. Irradiation tests using the fundamental wave- ∗ Corresponding author. E-mail address: s.siano@ifac.cnr.it (S. Siano). length and the second harmonic of Nd:YAG laser were carried out on both authentic and prepared samples in order to optimize the treatment and achieve general criteria, which could be exploited for the broad class of fiber objects. 2. Introduction Ethnographic heritage includes various types of household items crafted using vegetable fibers, such as basketry, matting, ropes, brooms, brushes, and many others. For their production, sev- eral grass-like plant species (reeds, palms, cereals, etc.) have been used along the centuries. Parts of the plants (leaves or leaflets, branches, culms, stem) were and, in some cases, still are (living traditions) accurately selected and then processed using different techniques, such as drying, retting, beating, cooking, and combing. Depending on the final use of the object, twisting, spinning, plating and weaving methods were then used to process fibers in form of yarns, strands, and ropes [1–4]. Furthermore, very coarse materials such as striped leaves, stems, or other have often been employed for producing cordage without any specific preparation [5]. http://dx.doi.org/10.1016/j.culher.2017.02.012 1296-2074/© 2017 Elsevier Masson SAS. All rights reserved.