That Giotto's commitment to a reform of the Byzantine tradition was programmatic and total is demonstrated by the way in which he confronted the methodology of painting. It was a field in which innovation was difficult, because the only methods known were those handed down in the workshops and because in a technologically complex process like mural painting it was difficult to experiment with new materials that had not already been tried out, over a long period, in the workshop. We must remember that, at that time - and indeed long afterwards - the only way of judging the success of new materials or procedures was to examine their performance over time. Individual experimentation on a scientific basis did not begin until at least the early fifteenth century. And yet in the Arena Chapel a technique was devised to give the fictive marble panels of the dado and similar elements in the narrative panels the appearance of real marble. The effect produced by this technique is similar to that achieved later by so-called 'Roman stucco' or 'polished plaster' and, by all accounts, to that of ancient Roman encaustic murals, but there appear to have been no medieval precedents for it. Even without this particular instance of technical mastery, it is clear that the Arena cycle introduced a new way of executing mural decoration, both in terms of organisation and in specific technical procedures.
It is well known that already in the great Assisi cycle, from the Isaac scenes onward, the technique of painting a fresco based on giornate had replaced the a secco method (or at any rate the characteristic use of large areas or colour painted a secco) with its attendant structure based on pontate or scaffolding levels. This new method involved the rejection of the traditional, rigid graphic schemes developed over the centuries and codified in Byzantine manuals on painting, with the result that each new image required a new drawing. The master had the task of inventing the images and drawing them, while for the actual painting he often used assistants, of varying degrees of specialisation depending on their individual experience. There is insufficient evidence to prove that by Giotto' s time there were methods and instruments for transferring drawings on to the wall (like the later use of cartoons); but certainly there is no point in the cycle where the presence of the master cannot be felt (even if his hand is not always apparent). This suggests a rationally organised hierarchy within the workshop. Furthermore, a totally new system of painting was devised which permitted novel effects of softness and blending of colours - a system codified a century later in a treatise by the Paduan artist Cennino Cennini. Through the use of these highly sophisticated and complex techniques, most of which were hitherto unknown, Giotto was able to create in Padua one of the greatest masterpieces of European art, with a sureness of touch (in the entire cycles only a few pentimenti have been found) and a rapidity that are indeed extraordinary.

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Giotto a Padova

Thanks for the history lesson. Very interesting.