308 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[September, 



it is enl.irfjeil by squares to the full <limenslons, portion by portion : in this 

 case the pnper on u'hicli-if is copied shonlJ l)e iiKMierately tliin. for tlie con- 

 venience of tracing on the wall. A part of this " working" outline (as much 

 as can be finished in one painting) is now nailed to the wet v.all. and the 

 forms are again traced with a sharp point, which makes an indented outline 

 through the paper on the soft plaster. The " working" drawini; is generally 

 destroyed in this operation. [The following is another mode : the paper to 

 be applied to the wall is placed behind, and inclose contact with, the finished 

 cartoon ; the outlines of the latter are then pricked, and the operation neces- 

 sarily leaves a similarly pricked outline on the paper behind. The next pro- 

 cess is to pounce the [iricked outline of the latter, when fastened to the wall, 

 with a little bag of black or red dust : this leaves a dotted outline on the wall. 

 This method is sometimes adopted for small works, as the surface of the 

 plaster thus remains undisturbed.] The first mode — tracing on oiled paper 

 and then again from it to the wall— is. however, generally preferred, since it 

 ensures the best .and most decided outline, while the finished cartoon may be 

 preserved uninjured. In many celebrated Italian frescos the indented outline, 

 produced by tracing, is apparent.* 



It has been already observed that the fresco is a final o|ieration ; any cr;n- 

 biderable alterations that may suggest themselves when the cartoon is com- 

 |)leied must be made on the cartoon, or rather on additional pieces of paper 

 fitted upon it. 



[One of the most interesting examples of the nature and extent of the 

 alterations that may be introduced in a composition prepared for fresco, is 

 the cartoon, already referred to, of Ranhael's .School of Athens. The changes 

 are mostly additions. The figure of Epictetu.^, represented in the fresco sit- 

 ting in the foreground on the left, leaning his head on his hand, is wanting 

 in the cartoon. This figure was added to fill up a vacant space, .and thus the 

 charge, though a considerable improvement, involved no inconvenience. 

 .Some less important alterations in the same fresco, such as covering the head 

 of Aspasia with drapery instead of showing her flowing tresses (for thus she 

 appears in the cartooi'i), might have been m.ade on the wall without any 

 change in the drawing. That this cartoon was ihe identical one which served 

 for the execution of the fresco is proved by the exact conformity of every 

 part, except the additions above mentioned, with the painting.] 



Beside the Cartoon, in which the forms and general light and .shade are 

 determined, it is desirable to have a coloured .sketch of the whole composi- 

 tion, for it is almost as impossible to change colours as forms after Ihe fresco 

 is done. In general, the German painters are not in the habit of making 

 complete coloured sketches for this purpose. 



The Preparation of the Wall—\iX\\^ wall to be painted is covered with old 

 mortar, the ingredients of which are unknown, this coat should be entirely 

 removed till the solid materials are Laid bare. The rough coat then applied 

 is composed of river sand and lime. The proportions of the sand to the 

 lime may vary in difierent climates, and the working builder and mason are 

 sufficiently experienced on this point. In Italy, it appears that two parts of 

 sand were added to one of lime ; the Germans generally use more sand, viz., 

 three parts to one of lime. The thickness of the coat'is such as is generally 

 useil in preparing the walls of dwelling-houses. The surface of this first 

 apjilication should be rough, but not unequally so ; and the mason should 

 avoid leaving cavities in it. 



The wall thus prepared should be suffered to harden perfectly ; the longer 

 it remains in ihis state Ihe safer it w ill be, especially if the lime used was in 

 the first instance fresh. In that case, two or three years even should elapse 

 before any subsequent operations are undertaken. Among the essential con- 

 ditions of fresco painting must be mentioned the preparation .and seasoning 

 of the lime. At Munich it is made and kept as follows:— A pit is filled with 

 clean, burnt limestones, which, on being slaked, are stirred continually till 

 the substauoe is reduced to an impalpable consistence.* The surface having 

 settled t) a level, clean river sand is spread it over to the depth of a foot or 

 more, so as to exclude the air, and lastly the whole is covered with earth. 

 The German painters suffer the lime to remain thus for at least three years 

 before it is used either for the purposes of painting (for lime is the white pig- 

 ment) or for Coating the walls. Cornelius prepared the lime for the Ludwig- 

 Kirche eight years belore he painted there. A great quantity is generally 

 kept in Munich, and might, perhaps, be had from thence for works in this 

 country. The late Lord Monson intended to have had lime from Munich for 

 the works which Cornelius was to have done for him at Gatton. The pits or 

 vats in which the lime is preserved are not lined with brick nor protected in 

 any way ; they are dug in the mere earth. The lime thus kept is found 

 moist, as at first, after many years. Cornelius said that there might per- 

 haps be no objection to lining the pits, so as to kee|i the lime clean, but that 

 the usual moue was to slake it and keep it in the mode describeil.f 



The ultimate preparation for painting on the dry, hard, well-seasoned 

 mortar is as follows :— The surface is wetted again and again, with v.ater that 

 has been boiled, or with rain water, till it ceases to absorb. Then a thin coat 

 of plaster is spread over that portion only which is to be painted; the sur- 

 face of this coat should be but, very moderately rough. As suon as it begins 

 to set (in ten minutes or so according to the season), a second thin coat is 

 laid on somewhat fatter, that is, with more lime and less sand,— about equal 

 proportions. Both these layers together are scarcely a quarter of an inch 

 thick. The plaster is laid on and ihe .surfaces are smoothed with a wooden 

 trowel— this at least is C'ornel'us's practice. .Some painters like the last sur- 

 face (which is to rerelve the fresco) to be perfecily smooth ; one of the modes 

 of rendering it slightly rough is to fasten some beaver nap to the trowel : 

 another is to pass over the plaster in all directions lightly with a dry brush. 



* The outlines of Ilaphael's cartoons are covered with pin-holes. This is 

 very apparent also in the fragment of the cartoon for the -Murder of the Ju- 

 nccents now in the National Gallery. Of the cartoons above mentioned, by 

 Ago3iii'oCaracci,one (the IVium|ih of Galatea) has the pricked outline; the 

 otiier (the Cefdialus and Aurora) not. 



t The Italian mode, described in another paper of the Appendix is some- 

 what (lideient 



I I'rofcssor Hess directs the lime to be kept in pits liued «ilh brick. 



The process of Painiiu^. — A portion of the outline is now traced with a 

 sharp point on the plaster as before described, and tlie painter begins to work 

 when the surface is in such a state that it will barely receive the impression 

 of the finger, and not so wet as to be in danger of being stirred up by the 

 brush ; besides other inconveniences this would fill the brush «ilh sand. If 

 the wall has been previously well wetted, the plaster w ill not dry too rapidly ; 

 but if, during the course of a dry summer's day the surface begins to harden 

 too much and no longer takes the colour well, the painter takes a mouthful 

 of water from time to time and sprinkles it over the surface, in the same man- 

 ner as sculptors sometimes wet their clay models. Much evidently depends 

 on the thorough wetting of the dry mortar, before the last preparatory coats 

 are applied. 



In p.ainting, it will be found that the tints first applied sink in and look 

 faint, and it is necessary to go over the surface repeatedly before the full 

 effect appears. But after some time, especially if the surface be not occa- 

 sionally moistneed, the superadded colour will not unite with what is under- 

 neath. The change m some of the colours from the wet to the dry state can 

 be best learned by experience, but it is usual to try the tints at first on a 

 brick or tile that absorbs moisture. 



After having completed the portion allotted to the day, any plaster which 

 extends beyond the finished part is to be removed, and in cutting it away 

 care must be taken never to make a division in the middle of a mass of liesh, 

 or of an unbroken light, but always where drapery, or some oljject, of its 

 own outline forms a boundary ; for. if this be not attended to, it is almost 

 impossible, in continuing the work the next day, to match the tints so that 

 the junction shall be imperceptible ; but by making these junctions correspond 

 with the outlines of the composition, the patchwork which is unavoidable is 

 successfully concealed. 



In the next day's operation the surface of the old mortar is to be wetted 

 as before, and care must be taken to wet the angles round the edge of the 

 portion previously painted. This requires to be done delicately with a brush, 

 in order to secure the sufficient moistening of every minutest corn r, and also 

 to avoid wetting or soiling the surface of the finished portion. On this last 

 account it is better to begin from the upper part of the wall ; for, if the lower 

 part is first finished, the water constantly runs over the fresh painting. 



When the painter is unable to finish a portion at once, or is compelled to 

 leave it during the day for a considerable lime, the Munich artists have a 

 contrivance which arrests the drying of the work. A board is padded on 

 one side, the cushion being covered with waxed cloth ; a wet piece of fine 

 linen is then spread over the fresh plaster and painting, and pressed to the 

 surface of the wall by the cushioned side of the board, while the other side 

 is buttressed firmly by a pole from the ground. 



When any defect in the first operation is irretrievable, the spoiled portion 

 is carefully cut out and the process above described is renewed for that par- 

 ticular part. The s.ime remedy is possible in reviewing the finished work, 

 but here again care should be taken that the portion cut out should be bounded 

 by definite lines, for tiie reason before given. This attention to the nice ad- 

 justment of the successive portions of the work, so as to make one whole in 

 the mere execution, is of great importance in fresco [lainting. 



In the finished Iresco the <lepth of shadows is often increased, parts are 

 rounded, subdued and softeneil. by hatching, in lines of the colour required, 

 with a brush not too wet ; the medium then used being vinegar and white of 

 egg. Shade is more easily added in this way than light, but some use cray- 

 ons made of pounded egg-shells to heighten the lights. It is to be observed,, 

 that such retouchings are useless in frescos painted in the open air, because 

 the rain w ashes them au ay, w hilst the rain does not alfect frescos painted 

 w iihout retouchings ; of this the paintings on the Isar-Thor at Munich are a 

 sufficient proof. [Cavaliere Agricola who, as before observed, has lately 

 published a report on the Roman fresci s, is of opinion that they were re- 

 touched with coloured crayons.' V.asari.t however, distinctly says that 

 frescos wliich were not retouched were least subject to alteration and decay.] 

 Various methods of this kind have, nevertheless, been resorted to by the 

 Munich painters, and Cornelius has mentioned some 



The Colours and Implements. — These details, communicated with all-sufficient 

 precision by Cornelius, need not be inserted here, as they are given in other 

 pa[)ers that follow. The colours are chielly sim[de earths ; no vegetable, and 

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

 rendering vermilii.n durable. The palette is of tin. with a rim round it to 

 prevent the colours, which are thinned with water, from running oil. The 

 colours, mixed or ground in water, are kept at hand in small pots. The 

 brushes are of the usual materials, but they should all be somewhat longer 

 in the hair than those used for oil-painting. 



T Introducione, c. 19, and Vita di Antonio Veneziano, 



(To be continued.) 



MARTIN'S PATENT CEMENT. 



Upon visiting the Sun Fire Office now erecting under the superintendence 

 and from the designs of .Mr. Cockerell, we were much gratified by the 

 superior execution of the internal ornaments, which so far as the unfinished 

 state of the building would allow us to inspect them, and leaving design out 

 of the question, were singularly neat and perfect. Indeed we have scarcely 

 ever seen mouldings present so finished au appearance. The great objection 

 to panelled walls has hitherto been the very heavy expense consequent upon the 

 employment of such mode of embellishment. The mouldings are run and 

 the walls covered with a cement called Martin's Patent Cement, and present 

 a surface nearly as smooth and hard as glass; it is applied in much the 

 same way as any other Ci'ment. 



