Brémaud Iris, Cardon Dominique, Backes Bernadette, Cabrolier Pierre, Guibal Daniel, Langbour Patrick
CoRé (Conservation/Restauration, Revue de la SFIIC : Section Française de l’Institut International de Conservation), (2021) CoRé NS 1 :61-84
(Présentation de la revue sur le site de la SFIIC) / (Lien vers le N°1 de CoRé Nouvelle Série)
Brémaud Iris
Jardins de France (Société Nationale d’Horticulture de France) (2020) 660 (Grand angle: du sol au la – de la plante à la mélodie): 29-33
https://www.jardinsdefrance.org/ethno-bio-mecanique-des-bois-choisis-en-lutherie/
Cardon Dominique, Brémaud Iris, Quye Anita, Balfour Paul Jenny
The Textile Museum Journal (2020) 47:9-28
Abstract: This paper presents some aspects of the contribution to the history of colors and dyeing technology to be expected from the comprehensive study of a rare type of historical document, which was not published and exploited until recently. It describes and compares several early– to mid–eighteenth century manuscripts of dye books or treatises on dyeing from England and France, having in common an essential feature: all are illustrated with scores of samples of dyed wool fabric. The French sources are the Memoirs on Dyeing of two dyework owners in wool broadcloth–producing centers in Languedoc in southern France. The English sources belong to the Crutchley Archive and consist of the dye books of a family-run dyed wool fabric business in Southwark, London. In this paper, the authors first present the respective color gamuts of the French dyers and their contemporary colleagues in London. The study is based on correlations between the color names given to the samples in the documents, the corresponding dye recipes, and the chromatic specifications of the samples that were obtained through colorimetric measurements and expressed in the CIE L*a*b* and CIE LCh° systems of color description. Madder red is then proposed as a case study for comparisons of the dyeing processes and resulting chromatic effects in the English and French sources.
9èmes Journées du GDR Sciences du Bois – « multifonctionnalité des forêts et diversité des usages du bois » , 18-20 Novembre 2020, Grenoble/100%Distanciel.
Information et programme des journées: https://gdr-bois-2020.sciencesconf.org/
Animation d’un Groupe de Travail:
Présentation de 2 Posters:
Brémaud Iris and Gril Joseph
Holzforschung Ahead of Print. (2020)
DOI: https://doi.org/10.1515/hf-2020-0029
Abstract: Moisture changes cause transient effects in various polymeric materials. In wood, they are mainly documented in semi-static or low-frequency domains and could explain various anomalies in wood behaviour, including the so-called mechano-sorptive effect. This article aimed at exploring and quantifying transient effects in wood vibrational properties, evidenced but in few publications. A series of 65 experiments on spruce and maple, in longitudinal (L) and radial (R) directions, spanning many humidity trajectories, were monitored through time (1–7 weeks) after step-change in relative humidity (RH). Changes in dimensions and specific dynamic modulus of elasticity (E′/γ) closely followed change in moisture content (MC). But the damping coefficient (tanδ) always increased (whether MC increased or decreased) within first hours/days, before slowly re-decreasing. This was quantitatively analysed by subtracting equilibrium moisture content (EMC) dependence from the global changes in tanδ, which simultaneously expressed destabilisation, followed by physical ageing (a slow process towards approaching equilibrium). For small EMC steps, the amplitude of destabilisation in L tanδ exceeded changes due to EMC dependence. Destabilisation was of similar importance relative to L or to R tanδ, while R tanδ showed much (2−4×) stronger EMC dependence. Amplitude of destabilisation increased with wider RH/EMC-steps (and faster sorption rates). Within an experiment, maximum destabilisation occurred nearly concomitantly with maximum sorption rate. Equilibrium was usually reached in MC, even within one week, but seldom in tanδ, even after several weeks. Results suggested that: (i) drying caused similar amplitudes of destabilisation, but that occurred sooner, and recovered faster, than humidifying; (ii) small RH-steps caused relatively smaller amplitudes of destabilisation, but that occurred later, and spanned over longer time before recovering equilibrium, than wide RH-steps. Some possible hypotheses are introduced to explain the observed phenomena. These phenomena also have important practical consequences in real-life wood uses and, particularly, in the design of experimental protocols
Keywords: Anisotropy; damping by internal friction; destabilisation by moisture sorption; dynamic mechanical properties; physical ageing; transient effects; viscoelastic vibrational properties .
Journées Facture Instrumentale et Sciences (JFIS) – « Matériaux et Procédés. » , 15-16 Octobre 2020, à l’ITEMM (Pôle d’Innovation Facture Instrumentale, Institut Technologique Européen des Métiers de la Musique) .
Information et programme de la journée: en suivant ce lien
Présentation d’une conférence:
Résumé: Les bois employés en facture instrumentale recouvrent une large diversité, selon les fonctions (familles et parties d’instruments) considérées, mais aussi selon les cultures (historiques et géographiques), et selon les préférences propres à chaque culture, voire à chaque artisan. Ces choix de bois font appel à un large éventail de paramètres, allant de la disponibilité des espèces, à des critères physiques, mécaniques et « acoustiques » très exigeants, en passant par des paramètres de « travaillabilité » et de « sensorialité » des bois. Mais de nombreux bois actuellement préférés en facture instrumentale viennent d’espèces en voie de raréfaction. La multiplicité des critères et implications des choix de bois en facture instrumentale en fait une sorte de « miroir à facettes » de la crise actuelle de biodiversité. Cette présentation vise à proposer un état de l’art des propriétés matérielles, notamment vibro-mécaniques, de bois importants en facture instrumentale mais en voie de raréfaction. Un accent particulier sera porté sur les Palissandres (genre Dalbergia et genres botaniques proches). En dépit de l’importance emblématique de ces bois, très peu de données sont actuellement disponibles dans la littérature sur les propriétés de ces bois. Après avoir établi la synthèse de ces informations existantes, de nouveaux résultats sur la diversité des propriétés vibratoires des Palissandres seront présentés. Ces résultats sont basés d’une part sur des échantillons collectés grâce à la participation active de plusieurs luthiers Français, d’autre part sur une analyse des échantillons de la xylothèque (collection botanique de bois) du CIRAD-Montpellier. Ce travail fait partie d’un projet en cours, international et inter-métiers, visant à comprendre les spécificités des Palissandres.
“Sharpening the scientific tools for violin making”, Online conference organised by Claudia Fritz, Institut d’Alembert, Sorbonne Université – CNRS, Paris, 5 – 9 October 2020. Program.
Videos of the global event: https://www.youtube.com/playlist?list=PLuRDiBz-vRGnJSGfYsvsfFkLBQrYkLOan
Video of Iris Brémaud’s talk: https://www.youtube.com/watch?v=KEvNPU0dmM0&list=PLuRDiBz-vRGnJSGfYsvsfFkLBQrYkLOan&index=9
Online conference on the 6th of October 2020:
Abstract:
“Tonewoods” could be primarily defined by their historical processes of selection – and current processes of choice – by instrument makers. Yet, understanding the causes underlying these selection processes, as well as some consequences resulting from these choices, calls for a wide span of disciplines. In this talk, I will present a possible methodology to bridge the craftsmanship uses and knowledge of tonewood, together with wood science (in the wide sense of the term) and some insights from social sciences and humanities. The proposed methodology is organised in 5 steps that form a “loop”: (1) Surveys with artisans to collect wood knowledge and encountered issues; (2) Identification of underlying physical-mechanical phenomena; (3) Exploration of the diversity and variability of wood species and properties; (4) Physical-mechanical consequences of processes and treatments used in craftsmanship; (5) Analysis of the sensory perception of wood variability and properties by its expert users. After an introduction to the basics of wood physics, the different steps of this transdisciplinary methodological approach will be illustrated by an array of research, grounded upon analytical review of literature of the past decades, and continued by research we recently conducted on wood uses by musical instrument makers, with a focus on luthiers of string instruments, and occasional illustration from other organological families.
Brémaud Iris and Gril Joseph
Holzforschung Ahead of Print. (2020)
DOI: https://doi.org/10.1515/hf-2020-0028
Abstract: This article aims at providing a synthetic view of the equilibrium moisture content (EMC) dependence of wood vibrational properties (i.e. dynamic mechanical properties in the audio-frequency range), including specific dynamic modulus of elasticity (E′/γ) and damping coefficient expressing internal friction (tanδ). A series of multi-trajectories experiments was designed to complete an analytical review. Literature indicates that: (1) in longitudinal (L) direction, the EMC dependence of E′/γ shows a very consistent shape (rather linear) between studies, while its shape is non-linear for tanδ and varies significantly between studies; (2) EMC dependence of tanδ is rather well documented in the L direction, in adsorption, for softwoods, but data covering EMC dependence in both L and other anisotropic directions, and sorption hysteresis, are still scarce. Experiments were conducted on a softwood (spruce) and a hardwood (maple), in L and radial (R) directions, in full adsorption from oven-dry state, full desorption from water-saturated state, and relative humidity (RH) loops without extreme conditioning. Measurements were made at conditions considered “at equilibrium” and some were monitored through time. Results indicated that tanδ was much more (×3) sensitive to EMC differences than E′/γ. R properties, especially tanδ R, were much more (×2–3) sensitive than L properties – resulting in strong increase of anisotropy with increasing EMC. In L direction, differences due to EMC remained moderate compared to the natural variability of wood for E′/γ, while for tanδ the EMC-induced changes were at least equal to natural variability in high-grade spruce. Vibrational properties did exhibit a hysteresis as a function of RH, but very little hysteresis as a function of EMC. The tanδ-EMC relation strongly depended on the actual time of stabilisation after reaching EMC. A related paper will address the transient, out of equilibrium effects of changing moisture conditions on the vibrational properties of wood.
Keywords: Anisotropy; damping by internal friction; equilibrium moisture content dependence; sorption history; specific dynamic modulus of elasticity; viscoelastic vibrational properties .
Karami Elham, Bardet Sandrine, Matsuo Miyuki, Gaff Milan, Brémaud Iris and Gril Joseph
Composite Structures, 2020, 253, pp.112736
Abstract: Spruce wood specimens were treated under mild temperatures 130°C and 150°C and different relative humidity from 0% to 25%. EMC reduced significantly for all the treatments. Weight loss (WL) increased insignificantly while the colour parameter, L*, decreased dramatically. Tanδ reduced significantly while the E/d has increased. After reconditioning, the partially reversibility has been achieved for EMC, tanδ and E/d. But, still an irreversible changes remains, which suggested being due to the chemical changes in wood polymers. While reversible changes has been resulted from the annealing of amorphous polymers. Since, the mild hygrothermal treatment applied to the specimens coincided with no significant WL, there was no obvious damage in wood structure while the irreversible changes present an improvement in vibrational properties by decrease in damping (tanδ), which could be due to the intermediate relative humidity of the treatment.
Keywords: mild treatments, weight loss, colour parameter, reversible effects, reconditioning, damping .
.
Visite des laboratoires Bois du LMGC et de l’Unité BioWooEB du CIRAD par les élèves en lutherie en guitares, professeure Martine Montassier, Lycée Fernand Léger de Bédarieux , 29 Janvier 2020.
