Which came first the egg (tempera) or the antependium?

How did polyptichs appear? Was the Byzantine Icon to move to the altar, or was it the antependium? Why from preparing the wooden panels with parchment and two layers of gesso, gilding became limited to frames? What are the roads followed by icons and art objects in their passage from East to West? How was the Platonic-Byzantine concept of the image received in Europe and how was it transferred into the more Aristotelian sphere of Western medieval culture?
“Paths to Europe, From Byzantium to the Low Countries”, edited by Bernard Coulie and Paul Dujardin, Silvana Editoriale, just published, 53rd  volume of the Biblioteca d’arte series, tries to answer some the these questions and it is also the summary of a conference held in BOZAR, Brussels in January 2015.
Inside the volume, the article “Under the Gold: a Database of Underdrawings and Material Analyses on Sienese Paintings. Connections and Dissimilarities in Painting Techniques across Centuries and Countries”, presents the peculiarities of Sienese paintings between the twelve and the fourteen centuries. Changes in style but also in the techniques and materials used, emerge from the analysis of the Art-Test database on IR reflectographies, X rays and chemical analyses on 100 paintings of Pinacoteca Nazionale of Siena. The passage from the archetypical, not to be changed model of the Byzantine icon to a free hand spontaneous underdrawing, from the gold background imitating goldsmith and from the 7 colours of the Palatinus codex to the oneiric pinks of the Sienese paintings is illustrated. Presenting also how X rays can be studied to understand the function of a painting on wooden panel, the paper exemplifies how changes in style and the messages that the paintings were to convey are closely connected with the evolution of the techniques employed to physically make them.