Resumen de Altarpieces in Portugal: joinery techniques within the context of fifteenth- and sixteenth-century European workshop practice
This contribution presents research on joinery techniques used in fifteenth- and sixteenth-century altarpiece in Portugal, commissioned by Portuguese bishops, kings and nobles. A large group of panels was investigted by careful examination "in situ" (in cathedrals, churches, museums and conservation laboratories) and by studying X-radiographs and conservation treatment reports. Wood identification was carried out with optical microscopy and the metal alloys used in the construction were identified by scanning electron microscopy coupled with energy dispersive X-ray analysis.
A comparison between altarpieces made in, or imported into, Portugal with those made in other European countries revealed rare as well as common joinery techniques, permitting the identification of possible origins and influences. This investigation demonstrated that there were more techniques being used in workshops in Portugal in the sixteenth century than had been identified in previous studies. In addition to a carpenter, a smith was also involved in the altarpiece construction. In Portugal, aside from cylindrical dowels or splines (small rectangular pieces of wood) locked by transverse dowels, other joinery system employed: inserted dovetails; hotizontal crossbeams attached to the boards by transverse cylindrical wooden dowels or carbon-iron nails; unlocked splines; cylindrical dowels alternating with unlocked splines (mixed system); cylindrical dowels alternating with dovetails (another mixed method); splines set into the panel and secured with 10 cylindrical dowels; and conical dowels (found on an altarpiece in Portugal in cedar, a wood mentioned in only a few Portuguese publications in the literature). The last five types seem to be peculiar to altarpiece from workshops active in Portugal.
