213 



FRESCO PAINTING. 



FRESCO PAINTING. 



214 



of the Virgin, in Santa Maria di Castello, painted by Justus de 

 Alemania, or Justus of Germany, in 1451. The lime used by the 

 fresco painters of Munich ia made of the marble pebbles brought 

 down from the Bavarian Alps by the Isar. Excellent limestone for 

 the purpose is found also in England, on Durdham Down, in the 

 neighbourhood of Bristol, and in other parts. Analyses of all these 

 and other varieties are given in the Reports of the Commissioners of 

 the Fine Arte. 



Modern fresco painters recommend the lime to be kept a much 

 longer period than Cennini and other early writers direct. If used too 

 fresh, it blisters, and sometimes turns the colours to a brownish red ; 

 its caustic quality requires to be mitigated, but not destroyed, before it 

 is used. On this subject Sir Charles Eastlake's Report contains several 

 scientific observations, upon the authority of Mr. R. Phillips, from 

 which we learn that the non-caustic state of lime is arrived at when, 

 by exposure to the air or by other means, it is restored to the state of 

 a carbonate or has regained its maximum of carbonic acid. If buried 

 and kept air-tight, it cannot acquire the carbonic acid which renders it 

 non-caustic. Time therefore has no effect on pure lime, whether 

 slaked or unslaked, provided it be not exposed to the air or some other 

 source of carbonic acid. 



The lime used for the intonaco in fresco painting must, however, not 

 be entirely carbonated, or it would not set; a certain degree of 

 causticity is necessary how much, however, can be learnt probably 

 by practice only ; and this is the greatest practical difficulty in the 

 art. The picture must be executed while the intonaco is wet or soft; 

 no more work therefore ought to be commenced than can be com- 

 pleted within the time (a few hours) that the plaster requires to 

 harden. Numerous joints are thus necessary in a large fresco, and 

 the judicious painter will contrive that these joints shall be identical 

 with the inner outlines of the parts of the figures and their draperies, 

 or any other object, so as to be no disfigurement to the work. 



Cornelius recommends the following mode of preparing the lime. 

 A pit, lined with brick, is filled with clean burnt limestones, which, 

 on being slaked, are stirred continually until the substance is reduced 

 to an impalpable consistence. Clean river-sand is then spread over the 

 surface, to the depth of a foot or more, and then the whole is covered 

 with earth so as completely to exclude the air. It is allowed to remain 

 in this condition for at least three years : it retains its moisture for 

 many years. It is excluded from the air, for the reasons assigned 

 above, that it may retain its causticity, and not become entirely 

 carbonated. But there appears to be no real necessity for keeping the 

 lime so long buried ; and river-sand should be used with great caution. 

 Wishing to employ a ground darker than the usual white intonaco for 

 some of the paintings he was engaged on in the new palace, Mr. Dyce 

 procured specimens of the dark gray sand of the river Lune in 

 Yorkshire, and " the result was encouraging." But desiring to be 

 assured as to its" chemical properties, he applied to Professor Hofmann, 

 who, on analysing it, discovered that the dark colour was attributable 

 to the presence of iron pyrites, and pointed out that an " intonaco 

 deriving its tint from such a cause, when exposed to the action of the 

 atmosphere, in likely to crumble much sooner than one in which sand 

 free from iron pyrites is employed." But as Sir R. Murchison 

 observed, river sands nearly always " contain impurities and oxidisable 

 substances which would be sure to affect the intonaco." " The analysis," 

 continues Sir Roderick, " of the old Paduan frescoes (of Giotto) shows 

 that there was scarcely a trace of iron in the Italian mixture, which 

 was, I dare say, made up of the purest silicious sand which could be 

 procured with one of the crystalline limestones or pure marbles of the 

 country, nearly all of which contain some magnesia. The sculptors 

 may aid the painters, and the rejectamenta of the former may prove 

 the best possible material for mixing up with the pure white sand, for 

 it is highly charged with carbonic acid. Besides, by this process one 

 half of the material would be Italian, and possibly, if not probably, the 

 very lime used by Giotto." (Eleventh Report.) This last is a hint 

 well worth attending to. 



3. Execution of the Preico. Cornelius recommends three years' in- 

 terval between the rough coating of the wall and the commencement 

 of the actual preparation for painting, unless the lime used in the first 

 instance be very old, when between six and twelve months will be 

 sufficient. Before laying on the inlmaco the prepared ground must be 

 repeatedly wetted with rain-water or boiled water, or still better, 

 distilled water, until it will absorb no more ; then a thin moderately 

 rough coat of plaster of sand and lime must be laid over as much of 

 the wet surface as can be painted in one day ; as soon as this coat 

 begins to set, in about ten minutes or so, another thin coat must be 

 lid on with a wooden trowel, somewhat fatter, that is, with more lime 

 and leas sand, .or with about equal parts of lime and fine river-sand ; 

 both layers together being scarcely a quarter of an inch thick. Upon 

 this coat the fresco is to be painted : if the surface as left by the 

 wooden trowel is found to be too smooth, it can be made slightly 

 rough with a dry brush. This in/raiaco will be fit to paint upon in 

 about a quarter of an hour : it is hard enough to receive the colour as 

 soon as it will not yield to the pressure of the finger ; it" too soft, the 

 wet brush will wash up the sand. The first process in executing the 

 picture is to pounce or trace the outline of the allotted work, from the 

 expressly prepared cartoon, of the same size as the fresco, upon the 

 intvnaco with a hard point (the artist must please himself as to the 



method of tracing); then the painting may be commenced in thin 

 watery washes, from the finished coloured sketch, which must be 

 placed so as to be conveniently seen while at work ; for the process of 

 fresco-painting should be simple copying ; the mere execution requires 

 so much attention, that it is necessary for the painter to be relieved of 

 every other consideration. After the first wash is finished, an interval 

 of twenty or thirty minutes should be allowed for the absorption of 

 the water before commencing the second painting, otherwise in 

 retouching and elaborating the design the surface would be washed up 

 and the work destroyed. While the intonaco is wet, a repetition of 

 the same tint will have the effect of a darker tint, as in water-colour 

 drawing : the retouches for strengthening and rounding should be 

 hatched, and, where great depth or force is required, repeated 

 hatchings are necessary. The surface must be constantly kept moist 

 (but not wet) while painting, or the superadded colour will not unite 

 with what is beneath ; the work is finished by glazings and washings. 

 When the portion of the picture allotted for the day's work is com- 

 pleted, the superfluous portions of the intonaco should be carefully 

 cut away. In the next day's operation the surface must be wetted 

 as before, and the edging of the finished piece carefully moistened 

 with a brush. If it should be necessary to leave the work for an 

 hour or two, it may be kept moist by pressing a wet linen cloth 



r'nst it, by means of a board padded and covered with a waxed 

 h ; the board may be propped against the wall by a pole from the 

 ground. 



If a piece of work should be unsatisfactorily executed, or accidentally 

 damaged, it must be entirely cut away, and the whole operation be 

 commenced afresh. A fresco cannot safely be retouched when dry, 

 but if retouched the vehicle should be vinegar and the white of egg ; 

 this answers well for the shadows : the lights are sometimes heightened 

 by crayons made of pounded egg-shells. It is useless, however, to 

 retouch a fresco in the open air, as the rain would wash all retouches 

 away ; the fresco itself is not injured by rain. 



The colours used in fresco-painting are all ground and mixed in 

 water, boiled or distilled ; they are chiefly earths ; no vegetable and 

 few mineral colours can be used with safety, but there is a mode of 

 rendering vermilion durable. The white used is exclusively lime, 

 which has either been well washed and long kept, or, by boiling and 

 repeated manipulations and drying, is rendered less caustic. The 

 following colours are used by Hess, the eminent German fresco- 

 painter: yellow, all kinds of ochres, raw siena; red, all kinds of 

 burnt ochres, burnt siena, oxides of iron, and lake-coloured burnt 

 vitriol ; green, terra-vert, or Verona green, cobalt-green, and chrome- 

 green ; blue, ultramarine pure and factitious, cobalt. These colours 

 are perfectly safe ; chrome-yellow and vermilion are also used, but 

 not in every case with success. Lime destroys all animal and vegetable 

 colours. 



The tints should be carefully prepared and kept in pots, and if a 

 great quantity of any one tint should be required in one picture, it 

 should all be prepared at once, as it is almost impossible to match tints 

 exactly, as they are of different degrees when wet and when dry. 



The brushes are of the ordinary materials, but should be somewhat 

 longer than those used in oil-painting. In addition to hogs'-hair tools, 

 small pencils of otter hair in quills are used : other hairs will not 

 resist the lime, which burns and curls them. The palette, commonly 

 made of tin, with an edge to prevent the colours from running off, 

 should be covered with varnish, to preserve the tin from rust. 



To know when to leave off is a great art in oil-painting, but in fresco 

 it is of the utmost importance. On this subject Hess says, " If the 

 touches of the pencil remain wet on the surface, and are no longer 

 sucked in instantaneously, the painter must cease to work, for hence- 

 forth the colour no longer unites with the plaster, but when dry will 

 exhibit chalky spots. As this moment of time approaches, the 

 absorbing power increases, the wet brush is sucked dry by mere 

 contact with the wall, and the operation of painting becomes more 

 difficult. It is therefore advisable to cease as soon as these indications 

 appear. If the wall begins to show these symptoms too soon, for 

 example in the second painting, some time may be gained by moisten- 

 ing the surface with a large brush, and trying to remove the crust or 

 setting that has already begun to take place : but this remedy affords 

 but a short respite." 



Fresco-painting as thus described is sometimes termed by Italians 

 Ituon-fresco, to distinguish it from another method which they term 

 ! fraco-tecco, dry fresco. 



Fresco-iecco is practised at Munich as follows, as described in Mr. 

 Wilson's report : The plastering of the wall having been completed 

 as for buon-fresco, the whole is allowed to dry thoroughly. Before 

 painting, the surface of the intonaco must be rubbed with pumice- 

 stone, and on the evening of the day before the painting is to be 

 commenced, it must be thoroughly washed with water mixed with a 

 little lime ; it must be wetted again the next morning, and it is then 

 ready for pouncing or tracing the outline, and painting ; the wall must 

 be kept constantly moist by means of a syringe. The colours used are 

 the same as in luon-fretco, and the work is very durable. All fresco 

 painters do not trace their outlines from cartoons, but it is the safest 

 practice, and has been adopted by all the best masters. Fresco-seem is 

 a good method for decorative painting, for which it is now much 

 employed. 



