CHAPTER VI. (XX.)
Of Painting in Tempera,[[198]] or with egg, on Panel or Canvas, and how it is employed on the wall which is dry.
§ 82. Painting in Tempera.
Before the time of Cimabue and from that time onwards, works done by the Greeks in tempera on panel and occasionally on the wall have always been seen. And these old masters when they laid the gesso ground on their panels, fearing lest they should open at the joints, were accustomed to cover them all over with linen cloth attached with glue of parchment shreds, and then above that they put on the gesso to make their working ground.[[199]] They then mixed the colours they were going to use with the yolk of an egg or tempera,[[200]] of the following kind. They whisked up an egg and shredded into it a tender branch of a fig tree, in order that the milk of this with the egg should make the tempera of the colours, which after being mixed with this medium were ready for use. They chose for these panels mineral colours of which some are made by the chemists and some found in the mines. And for this kind of work all pigments are good, except the white used for work on walls made with lime, for that is too strong. In this manner their works and their pictures are executed, and this they call colouring in tempera. But the blues are mixed with parchment size, because the yellow of the egg would turn them green whereas size does not affect them, nor does gum. The same method is followed on panels whether with or without a gesso ground; and thus on walls when they are dry the artist gives one or two coats of hot size, and afterwards with colours mixed with that size he carries out the whole work. The process of mixing colours with size is easy if what has been related of tempera be observed. Nor will the colours suffer for this since there are yet seen things in tempera by our old masters which have been preserved in great beauty and freshness for hundreds of years.[[201]] And certainly one still sees things of Giotto’s, some even on panel, that have already lasted two hundred years and are preserved in very good condition. Working in oil has come later, and this has made many put aside the method of tempera: in so much that to-day we see that the oil medium has been, and still is, continually used for panel pictures and other works of importance.