The Perseus
Now I have to repeat, then, that the clay figure must have a kind of paste spread over it with a very soft paint brush, & little by little the foil is laid upon it. This paste is made of flour dust, and prepared in the way shoemakers do it, or the mercers, when they make barettas & satchels and such like, and you must mind to make it very fine and thin, and when you have put the foil in little pieces all over it and the whole figure is covered, you can make your gesso mould.
There are divers ways of making the gesso moulds. The best, however, that I have come across and that I mostly use myself, is to make as many small pieces as when put together would make a complete man, and that without any undercutting—as for instance feet, hands, head. These small pieces must be made with great care; and while the gesso is moist you fit into each of them an iron wire bent double, and projecting out of the gesso much like a little ring, so as to be capable of holding a thread through it. Each time that one of these small pieces is finished it must be tested, and you must see if you get a good impression from it & if the piece relieves. Then if you see that the impression relieves without spoiling a single trifle of your work’s delicacy, you put the piece in its place again, and with all a good master’s ingenuity take the next piece off it, leaving no rift whatever in between them such as would scar the work; & so you go on little by little, making the whole series of pieces, observing the undercutting and whatever is demanded for the head, hands, feet, &c. In this manner you carefully make your division right down one half of the figure, I mean the half, taken lengthwise, coming over the belly and the breasts down to the hips, and from the bottom of them to the half of the heels.[220] Mind, however, that with these small pieces the figure is not entirely covered, but leave a part of the breasts, a part of the body, a large part of the thighs, and as much of the legs. You must take care, too, that the pieces be so placed that they may be fitted together as one, but there must be no undercutting because over this half figure will have to be cast a coat[221] of fine gesso more than two fingers thick. Before doing this, however, you must mind to cover up with a little clay the iron rings which I told you before were to be put on the small pieces, so that in putting on the coat they do not hinder it from being lifted off. After this you carefully paint over with a brush of olive oil all such parts as shall come in contact with this coat in order that when the gesso is set the coat may easily relieve. When you have tried a piece to see if it will relieve, put it back in its place, and finish the other or back half of the figure in the same way as I bade you do the front. You must be very careful when you have finished your mould to take some strong thick cord and bind the whole figure together from top to bottom, putting a lot of little wedges of wood in order to tighten the rope yet more and prevent the gesso from twisting[222] and buckling. In order not to run any risk of such twisting you keep it thus bound up till all the moisture has gone from the gesso. When you see it quite dry you unwind the cord and open the mould, and that is your first mould.[223] This in small figures may be of two pieces only; when I say small figures I mean life size or less, these may be made in two pieces; if they be larger than that you must make them in four pieces, i.e., one piece on each side from the top to the navel, & another on each side from the navel to the bottom of the figure. In order to fit better together these pieces must overlap the one upon the other a distance of about two fingers. This all minutely accomplished, you proceed to open the mould and lay it back downwards on the ground, that is to say with the concave sides of it facing upwards, and you take off one by one all the little pieces sticking to the figure and put them into the cavities made by them in the mould;[224] at the same time removing the little bits of clay which you put on the iron rings; and in every place where the clay has left impressions, bore a hole with a small gimlet[225] into the mother mould, and attach to each iron ring a piece of strong cord. This cord you pass through the holes in the mother mould, and tie each piece up in this manner with a little splint of wood. When you have thus fitted all your little undercut pieces into the mother mould,[226] you grease the whole mould with soft lard, & proceed to give it what is technically termed the lasagna, which is a cake about a good knife’s back thick of wax or clay or paste.
This is made thus: you take a piece of wood and with the chisels cut out in it a square cavity the shape of a man’s palm and of the depth of a good knife’s back, more or less, in accordance with the thickness your figure is to have. Then you keep squeezing your cake (or lasagna) into this wooden shape, & apply it to the gesso mould of your figure so as to let one piece touch the other. Then you lay the two halves together on the ground side by side, and construct an iron framework which serves as a skeleton for the figure, and this must be made tortuously and in accordance with the direction of the legs, arms, torso, & head of the figure. This done, you take clay beaten together with shavings of cloth—the thin clay of which I told you before[227]—and little by little fit it round the skeleton, letting it dry, now by patient waiting, now by holding it before the fire, till the whole of your mould is filled. Then you test the two parts by repeatedly applying the one to the other. When this framework of earth and iron, which is called the kernel, nocciolo, fills the figure so completely as to tally all round with the lasagna, you take it out, bind it round with thin iron wire from head to foot and give it a good firing. Then you streak it over with a thin solution made of powdered bone and thin brick dust mixed with a little of the clay and cloth frayings, and apply it again to a rather slighter fire, this time so that the solution shall also be fired, then you take the lasagna out of your mould. You must be very careful, too, to leave some pieces of the iron skeleton sticking out in at least four places, for they will keep the kernel from shifting, and these projections must tally with the gesso mould. When the lasagna is removed you once more grease the gesso mould with fat, a little soft bacon fat is best, and it is also well to have it warm, for then it combines better with the gesso.
Then you make the inlet holes in which you want to pour your wax, and fit the kernel into the mould; then stand the figure up straight & make at least four vent holes, two at the feet and two at the hands, the more you make the surer you will be to fill your figure with wax.
The vent holes you make thus. The first two you place right at the very bottom of the feet, and it will be better for you to set your figure on a little eminence in order to do this more easily. You must take a stout gimlet,[228] and carefully bore a hole with it, and this is best done if slanting downwards, and see that you leave no fragments in the mould as you do it. When you have made these holes, you take a number of canes, which you skilfully bend, & so fit together that they start from the holes below and turn up straight alongside the figure, binding one cane to another & all together into one up towards to the top of the figure. You must be careful, too, wherever the bits of cane join, and wherever they fit into the holes, to smear them well round with a little moist clay so as to prevent the wax from oozing out.
After this you can heat your wax, &, when it is well molten, pour it in. This process now can be easily effected, however difficult the pose of the figure may be, if you observe the various little hints I have given you, & above all give heed to the vent holes at the base. After you have filled it with wax let it thoroughly cool for a whole day—if it be summer, say two days. Then undo the bindings with great care; & loosen all the little bits of string that tie the pieces together within, and are made for the undercuttings as I so carefully explained to you before. When you have uncovered the one half, you may complacently begin to try it from either front or back; & I tell you this, the fact of your having let the wax stand for that day or two according to the season of the year, will cause a slight shrinkage in the wax of about the space of a horse’s hair, and so you will find it quite easy to remove this first piece from your figure. Then lay it down, and proceed to do the like to the next piece, & you will do well to lay both on long narrow benches, so that you can get underneath them with your hands.
After this you remove from the figure all the pieces of the mould attached with the bits of string through the iron rings one by one ever so carefully, and you polish & remove very nicely all the rough edges that may have been left on the figure by reason of the joinings of all the different pieces, and in this manner you touch up the whole. In doing this, moreover, if you are minded to add any subtle labour or fancy to your work, you are easily able to do it. After this[229] you fashion in wax, just as you erst made them for the earthen mould[230] all the vent holes for the bronze casting, & mind that they all slant downwards to the bottom; later when the figure has its last & earthen mould on, these vents may easily be turned up with clay. The method of doing this I shall describe minutely later as soon as I have shown how all the different coatings[231] from first to last are applied, the mould bound up and the wax emptied out.
Here all I want to insist on is that the vents must be made to bend towards the bottom, because, when that is the case, the wax is more easily melted out; if they were otherwise you would have to turn the mould up and down, which would give trouble, & you would run risk of spoiling it. But if you do it as I tell, you are absolutely safe. Then note this too, it is of the utmost importance that in melting out the wax your fire be so tempered that the wax does not boil in the mould, but comes out with the greatest patience. When the wax is all out give the mould yet another but very moderate firing, in order to get rid of any moisture that may be left in the mould. Then you may give it a regular good firing, first casing the mould in a coat of bricks set one above the other, & at about a three fingers’ distance from the mould; this firing should be of soft wood, such as elder, lime, beech or twigs. Any green wood, or the wood of the oak, is to be avoided, and use no charcoal whatever, because all these fuse the clay and make it become like glass. There are some earths that do not thus cohere, and such are used in glass & bronze furnaces. I shall not fail in the proper place to tell you of these, but at present let me continue my narration of how to prepare our mould for the casting of the bronze.
Dig a pit near your furnace in front of the plug at the outlet hole,[232] which pit should be so big as not only to contain your figure, but also be half a cubit deeper, and in order that you can give the proper fall, the mouth or inlet hole[233] must be at least a quarter of a cubit above the head of your figure. So also as in the case of its depth, the pit should be half a cubit larger in width than would be needed to hold the mould. Then take the mould out of the bricks in which you baked it, and when it is cool bind it very carefully with a rope which should be strong enough to carry it, then fasten a pulley to a beam in the roof, & the rope through the pulley, and see that you provide a windlass sufficiently strong to lift your figure. As I don’t want to omit certain little details, which may be well learnt from experience, I may mention that when I made my Perseus, for that the work was so very large, I lowered it into the pit with two windlasses, which were weighted with more than 2,000 lbs., but a small figure of three cubits would not need more than one. ’Tis true you might do without any windlass at all for the latter, but that would be very risky, because it might tend to move the kernel of the mould, that is the core[234] or inner block, or again it might knock the shell[235] outside it. The windlass obviates this danger. And so you very very gently hoist the figure up, & move it to the mouth of the pit, & with equal care you unwind the windlass and lower it to the bottom.