With these three or more tints you begin to model your head, beginning with the dark parts and working up to the light. You must bear in mind that no rubbing out is possible; you cannot wash or sponge out as in water-color drawing.
You must therefore be very careful in approaching the light parts, and copy the cartoon as carefully as possible.
You continue thus to draw and model with your green color until the head looks like a finished drawing. This operation will take from two to four hours, according to the nature of the head.
You now take three clean tumblers and put a small lump of light red or terra rossa into one of them, add water, and mix as before; you make weaker solutions, just as you did with the green. If the head is that of an old man or a bronzed warrior, you ought to add raw sienna to the light red, but for ordinary complexions the light red is quite sufficient. You apply this flesh tint in washes with a very broad and soft brush, using the stronger solution for the lips and cheeks, the medium for the intermediate parts, and the weakest for the high lights. No modelling is required; the modelling has already been done, and this tinting is very soon accomplished.
You now take either burnt sienna pure, or burnt sienna and umber, and with a fine sable give strength and precision to the darkest parts, such as the nostrils, the division of the lips, the inside of the ears, etc. If a little black is necessary for the eyebrow or eyelashes, you now give these little finishing touches, and your head is complete.
You have not used one grain of lime or of any solid color; the wall is stained rather than painted, and you have none of those strange and capricious changes of color to fear which are so constantly occurring in the solid method, where lime is used freely as a pigment.
I have now gone through the whole process of fresco-painting as far as I know it. I shall conclude with a few general observations.
The fresco-painter ought to be of a nature capable of continued exertion. Whatever the work is, whether head, torso, or drapery, it must be finished in a day. He must not, on the plea of headache or seediness, give himself a half-holiday. He may of course abstain from work for a whole day, or for a week if he likes, but those little snatches of rest, involving a game at lawn-tennis, a good lunch, or a look at the papers, to which many artists are rather partial, are denied him.
He is always working against time, and although this is trying at first, he soon gets accustomed to it.
Secondly, he must be a man of fixed purpose. He has got his cartoon and his colored-sketch, and he must turn a deaf ear to all suggestions of alterations when once these preliminaries are settled.