Abstract Instrument makers prefer wood species which not only have excellent acoustical properties, but also tend to keep their natural state when going through preparations and pretreatments. In this study long time water soaking, a common protocol among Iranian lute makers, was used to investigate the natural durability and dimensional stability of White mulberry (Morus alba L.). The wood of white mulberry, which is the only source for making Iranian lutes for more than a century, was examined for its natural resistance towards fungi and termites. Samples were also studied for their dimensional change during four months of water soaking. White mulberry, whether leached or unleached, showed to be a very resistant species towards both termites and fungi. Gradual removal of the extractives during water immersion resulted in an increase in partial shrinkage. It was concluded that water leaching, though not affecting the natural durability, tends to reduce the dimensional stability of white mulberry.

Resumen Los fabricantes de instrumentos musicales (lauderos) prefieren madera de especies que no solo tengan excelentes propiedades acústicas, sino que además tiendan a mantener su estado natural durante su fabricación y pretratamientos. En este estudio se hicieron pruebas de inmersión en agua, un protocolo común entre los lauderos iraníes, para determinar la durabilidad natural y estabilidad dimensional de la madera de mora blanca (Morus alba L.). La madera de esta especie, la cual es la única que ha utilizado para la fabricación de los laúdes iraníes por más de un siglo, fue probada para determinar su resistencia natural al ataque de hongos y termitas. Los especímenes fueron estudiados para detectar cambios en sus dimensiones durante cuatro meses de inmersión en agua. La madera en estudio, lixiviada o no, mostró muy alta resistencia tanto al ataque de hongos como al de termitas. La remoción gradual de extractivos durante la inmersión resultó en un incremento en la contracción parcial. Se concluyó que, aun cuando la lixiviación en agua no afecta la durabilidad natural, tiende a reducir la estabilidad dimensional de la madera de mora blanca.

The wood used in making musical instruments usually undergoes pre-treatments or conditioning. Some processes have resulted from laboratory research, while many treatments are applied by craftsmen using traditional methods that have not yet been scientifically assessed. This paper is based on laboratory methods which simulate hydrothermal pre- treatments traditionally applied by Iranian lute makers to mulberry (Morus alba), an important wood for lutes from the Middle East to Japan. By applying a cyclic process, drying (60°C) and ambient re-conditioning, which mimics wood seasoning and short-term aging, the damping coefficient (tanδ) was decreased down to 10% without negatively affecting specific modulus of elasticity (E’/ρ). Long-term (up to 4 months) soaking in cold water removed extractives, and decreased density as well as E’/ρ, but did not affect tanδ. Short-term hot water treatment removed as many extractives, but caused a smaller decrease in E’/ρ than cold water, and significantly increased tanδ. This paper helps to clarify some traditional processes used by instrument makers, and can provide a basis for necessary cross-cultural scientific studies in the future.

No desenvolvimento de painéis, deve-se dar destaque a ensaios que remetam à aplicabilidade final do produto, como os ensaios de durabilidade ao ataque de fungos e cupins. Nesse contexto, painéis confeccionados com diferentes percentuais de partículas de bagaço de cana-de-açúcar (Saccharum sp.) e fibras de eucalipto (Eucalyptus grandis), aglutinados com duas dosagens de resina ureia formol (13% e 16%), foram submetidos à avaliação de resistência biológica (bioensaios) ao ataque de cupins e fungos, ensaio fundamental na definição de uso e aplicação do produto final. Foram utilizados cupins da espécie Reticulitermes santonensis, rhinotermitidade, e fungos da espécie Pleurotus ostreatus, basidiomiceto de podridão-branca, de acordo com procedimentos da normatização AFNOR. De modo geral, os novos painéis confeccionados apresentaram-se não resistentes aos bioensaios realizados e houve similaridade na dinâmica de ataque e perda de massa entre as diferentes dosagens de resina praticadas, remetendo à necessidade da aplicação de revestimento protetor na superfície dos painéis ou adição de produtos fungicidas e cupinicidas.

Trials referring applicability of the final product, such as durability tests to fungi and termites are crucial in developing panels. Therefore, panels made with different percentages of sugarcane bagasse particles (Saccharum sp.) and eucalyptus fiber (Eucalyptus grandis), bounded with two dosages of urea formaldehyde resin (13% and 16%), were evaluated for biological resistance (bioassays) to termites and fungi, which is fundamental in defining use and application of the final product. We used the termite species Reticulitermes santonensis, rhinotermitidade, and the fungy Pleurotus ostreatus, a white rot basidiomycete, according to AFNOR standardization procedures. In general, the new panels were not resistant to bioassays and there was a similarity in the dynamics of attack and mass loss among the different doses of resin applied, thus evidencing the need of applying protective coating on the panels surface or adding termiticide and fungicide products.