It requires considerable skill in the person who prepares this ground, to lay it perfectly even, and he must be very careful in judging of the quantity proper to be laid on at once. This ought not to be more than the painter can cover and completely finish in a day; and it requires great skill and activity in spreading. to clean it from Iii and polish it evenly, so as to receive the painting with the promptitude requisite to leave the artist as much time as possible. The painter, however, should himself superintend this part of the process, for he alone can judge properly as to the rapidity with which he can work, or the advantages he may make of accidental occurrences.
The operation of laying on the ground is performed with a trowel, and in doing this, care must be taken to clean it properly, that the surface may be even, particularly in those parts most exposed to view. The mason's labour is finished by his polishing the surface to receive the painting ; this is done by applying a piece of paper on the face ot' the wall, and passing the trowel over it. It is very necessary that this should be well done, for small inequalities in the surface might, in certain views, produce great irregularities in the drawing of the work.
When the second ground is thus prepared, cleaned, and polished, in the quantity, and on the part of the wall which the artist requires, he begins to trace his design upon it, and proceeds to the colouring of it ; completely covering the quantity prepared, and finishing so much of the picture in the course of the day, in such a manner that he may not have occasion to re-touch it when the ground is dry. This is the characteristic peculiarity of painting in fresco, which, by this mode of operation, is incorporated with the mortar, and dry ing along with it, becomes extremely durable, and brightens in its tones and colour as it dries.
From the necessity there is in the progress of this style of art, that it should be executed with rapidity, and from the impossibility of retouching it without injuring the purity of the work ; the artist, unless he be endowed with very extra ordinary powers of imagination and execution indeed, is obliged to prepare a finished sketch of the subject, wrought to its proper hue and tone of colour, and so well digested, that there may be no necessity for making any essential alterations in the design. This, which is a very useful mode of proceeding in all historic works of painting, is absolutely indispensable in fresco, to those who are not determined to give the rein to their ideas, and leave as perfect whatever may first present itself. There is no beginning in this, by
drawing the whole of the parts at one time, and correcting them at leisure, as is the custom in oil painting, where the artist may proceed to work without a sketch. Here all that is begun in the morning must be completed by the evening ; and that almost without cessation of labour, while the plaster is wet; and not only completed in form, but also (a difficult, nay, almost impossible task, without a well-prepared sketch.) must be performed, viz., the part done in this short time must have so perfect an accordance with what fellows, or has pre ceded of the work, that when the whole is finished, it may appear as if it had been executed at once. or in the usual mode, with sufficient time given to harmonize the various forms and tones of colour. Instead of proceeding by slow degrees to illuminate the objects, and increase the vividness of the colours, in a manner somewhat similar to the progress of nature in the rising day, till at last it shines with all its intended etffict, which is the course of painting in oil the artist working in fresco must at once rush into broad day light ; at once give all the force in light and shade and colour, which the nature of his subject requires. This, he it observed also. must be xs hitt tut the assistance (at least in the commence ment) of contrast to regulate his eye; and therefore may he considered almost impossible, as we have before said, unless he be assisted by a well-digested and finished sketch.
The sketch being completed, the next process is to prepare a cartoon or drawing of the design on paper pasted together to the size of the intended fresco. This cartoon should be peifected in the outline to save time, and the artist has then nothing to do hut to trace the line of the figures or other objects which the design may be composed of, on to the plaster, by either pricking with a pin through the paper, or by passing a hard point over the lines of the cartoon. By this means he saves himself the trouble of drawing the figures, and also the time which would be required for doing it, and proceeds at once to the painting; to thcilitatc the execution, and ensure the success of which, several precautions are requisite.