The treatises of Benvenuto Cellini on goldsmithing and sculpture

by Benvenuto Cellini

When the figure is standing in position, with the inlet hole[233] in a line with the plugs[236] at the outlet hole,[232] the first thing you have to do is to fit on to the vent holes certain tubes of baked clay such as are used for water-pipes. Of these there are plenty to be got in Florence, so that I was provided, and I used some of them bent, & those for the bottom pieces, and in all such instances when the vents were turned downwards; and fitting one tube on to another, I brought them into one straight line upwards.

This done, you take the earth you dug out of the trench and sift it well; then mix it with sand, which, however, ought not to be too soft, with this mixture you fill up the pit. The mixture of sand & earth it may be observed need only surround the figure to the extent of a quarter of a cubit, for the rest, the plain unsifted earth as you dug it out of the trench, will suffice to fill up the remainder of the cavity. When the earth has been piled in to the extent of about one-third of a cubit, you go into the pit with two rammers,[237] which are a kind of wooden instrument three cubits long & about a quarter of a cubit broad at the bottom. And with these you pound the earth and weld it well together. In doing this you must take great care in no way to knock at the mould, it will be quite sufficient if you come within four fingers of it, and instead of the rammers, press it with your feet, still take great care not to shake the mould. This ramming in you will repeat every time you have shovelled another third of a cubit of earth into the pit. Every time, too, that the earth fills up to the level of the top of the vents, take another of the terra cotta pipes and add it on, binding the juncture round well with a little clean tow in order to prevent the earth getting into the vents, for that would stop the passage of air and so hinder your figure from coming. In this way, taking heed of the vents as you fill in the earth, you pass from base to legs, from legs to flanks, from flanks to arms, till at last you get earth and vents on a level with the top of your pit. Then you proceed to make the passage[238] down which the bronze is to flow. Also you must take care that as soon as you begin putting your figure into the trench, you begin at the same time to fill your furnace with the bronze and heat it, so that your mould shall not get damp from too long standing. All these things if they be not observed ofttimes prevent the mould from filling.

When the pit is filled up to the mouth of the main entrance[239] where the bronze is to be poured in, and also having allowed for the necessary fall from the mouth of the plug[240] whence the bronze is to issue from the furnace, & having carried up all the vents as described, you keep both them and the mouth of the main entrance carefully plugged with a little tow. Then you take a lot of square tiles and make a pavement of them round the vents. As there will be more than one entrance channel for your bronze, you must take note that the flooring in question comes right up to the ingress holes of the bronze. Then you take bits of hard dry bricks broken up into pieces of three fingers or more in thickness, according to your cunning master’s discretion and according to the fall your bronze may need, & then these bricks you plaster together with liquid clay and cloth shavings in lieu of mortar, on the top of your flooring. Note further, that of these same bricks you construct a channel from the wall of your furnace and running right round the ingress holes of your figure.

Then you take bricks, baked or unbaked (the latter are better, though there’s not much difference)[241] and wall up the channel to the requisite height, the thickness of a brick wall will suffice. You construct it by laying brick upon brick & making the height of the wall equal the width of the channel.[242] When you have carefully joined together with your moist clay instead of mortar all the cracks through which the bronze might ooze out, you remove the tow plugs in the ingress holes of the bronze, and in their stead fit some easily removable stops of moist clay made so that you can take them out without difficulty, for you have almost immediately to bring glowing coals into your channel, and with these you cover all the parts that have been walled up with clay till they are well dried, and the fire must be renewed several times till they are not only well-dried but baked.

When all this is accomplished, and your metal meanwhile has got well fused, carefully blow with the bellows all the ash and cinders out of the channel, till none remains to hinder the passage of the metal; then take out all the plugs that close the vent holes, and the earthen stoppers in the ingress holes, & throw some two or three tallow candles, under one pound in weight, into the channel. Hereupon run to the mouth of your furnace and refresh it with a certain quantity of pewter of rather more than the ordinary alloy, i.e., half a pound per cent. (i.e., of bronze)[243] more than what you have hitherto used. When this has been very rapidly done, heap up more and more fire of green wood in your furnace, and then with your iron crook (mandriano) for thus the instrument is called, boldly strike away the plug of the furnace, & let the bronze run; gently at first, holding a point of the iron crook in the mouth of the plug, till a certain quantity of the metal has run forth, & its first fury be spent, for if you did not do this you might run the risk of your mould being stopped up with wind. Then you can remove the iron crook from the mouth of the plug and let all the bronze go till the furnace be emptied. To this end it is necessary to have a man standing at each of the furnace mouths, who, with the scraping iron[244] which is used in the craft, drives the bronze towards the outlet, until all is cleared out. Such of the flowing metal as is still left after your mould is filled you dam by means of throwing on to it with a shovel some of the earth you erstwhile dug out of the trench. That is how you complete your mould.

Not to be omitted are divers and terrible mishaps that occur from time to time, and often bring to nought all the poor master’s pains. So ’tis a wise thing to profit in good time by the experience of others. Ofttimes we figure casters call in the help of ordnance founders[245] to aid us, but the most terrible misfortunes not infrequently occur owing to their insufficient experience and want of care, and all our labour is lost. Just such a thing very nearly happened to me when I was casting my Perseus, for, calling to aid some of those fellows, I found them so absolutely devoid of sense that in their stupidity they all swore my mould was spoilt, and that there was no means of righting it, and all this thanks to the muddle they themselves had made with my metal.[246] The statue was more than five cubits high & its pose was a difficult one, for in its left hand it held raised aloft the head of Medusa, in the hair of which was much rich detail of serpents; while the right hand was held behind in a vigorous action, & the left leg was bent. All this variety of limbs made the casting most difficult, and for this reason I was ever so keen to get it good, and also because it would be the first big work I had produced in Italy, my fatherland, & the veritable school of all the arts. So I was moved to even greater pains and diligence than I had before used to complete my figure well. So, therefore, I set to making a great number of air vents, and ever so many flowing-in mouths that all diverged from one main one, the which ran down at the back of the figure from the height of the head down to both heels and spreading out a bit at the calves. All these little hints are part of the craft, and in this manner did I practise it when I wrought in France. As I had to do almost everything with my own hand, owing to the intense bodily fatigue to which I was subjected a violent fever seized upon me. I struggled against it for many hours, but in the end it floored me, and I was brought to bed. As I had those different masters of ordnance and statuary founders working for me, I explained to them before I laid me down, exactly the methods I had begun, and how these were now perfectly easy to understand, as more than half the figure was already covered, & the greater part of the difficulties surmounted. All that they had to do was to follow my instructions in detail, and that appeared easy enough, so, being utterly incapable of holding out any longer, I flung myself on my couch.

Meantime the men worked at my furnace which I had so well prepared and in which the bronze was nearly molten[247] and ready for completing. Now they had a good six hours’ work still to employ them in order to fulfil all my instructions in proper sequence, because they were not quite skilled in the technique of the craft, and because my methods were different from those they usually employed. Well, instead of doing what they were told they began larking about, neglected the furnace so that the metal commenced to curdle, or, as it is called in the craft, to cake, migliaccio they call it in their lingo. Nary a one knew a remedy for this blunder, for in a round furnace like this one the action of the fire upon the metal is from above, were it from below it would be easy enough to heat the curdled metal again; so not one of them knew a remedy. Then as I lay there prostrate on my bed with fever, one of them in whom I had a little more confidence than the rest, came to me, and speaking very gently, said: ‘Benvenuto, resign yourself to the worst, the furnace has been ill prepared,[248] a cake has formed on the metal.’

Then I turned myself toward him and had all the other craftsmen summoned in whom I put any confidence, and asked them if they knew any remedy. Whereupon these precious fine fellows said there was no other remedy but to break up the furnace, & in so doing, as the mould was buried six cubits in the ground, they could not see (they said) how the mould could help being spoiled. For even if I tried to dig up the ground round it, which had been plugged fast, there were so many ingress holes & vents that it was dead certain to be spoiled. That, forsooth, was the only remedy they had!

Now, gentle reader, picture to yourself my state,—I in all my ills & sickness—this new trouble thrust upon me—all my honour at stake—why I felt the keenest grief that ever man could imagine! But this was no time to give way to grief. Suddenly, as in a frenzy, my old inborn daring came upon me; it’s not a thing one can learn, this! it’s in a man’s nature! Furiously I leapt from my bed & literally frightened away that grievous fever with the biting words I shouted at those fellows.

‘Oh you good-for-nothings! who not only know nought, but have brought to nought all my splendid labours, at least keep your heads on your shoulders now and obey me; for from my knowledge of the craft I can bring to life what you have given up for dead, if only the sickness that is upon me shall not crush out my body’s vigour.’ Thus hounding them on I ran with them into the workshop, and in one go ordered six of them to different duties. First I bade one of them fetch me a load of dry oak that was stacked opposite the house of Capretta, the butcher; & as soon as this came I began throwing it into the furnace several pieces at a time. Now, though I’ve said it once before—as it’s so very important I’m going to tell it you again, & it’s this: in bronze furnaces the only woods you use are elder, willow, and pine, for all these are soft woods; in this particular instance, however, I used oak, because I wanted the greatest possible heat, and thus the metal began to move at once. To two others I bade with long iron rods to keep poking into the furnace mouths because it was storming with wind, and raining cats and dogs, & wind and rain was blowing into my furnace; by these means I showed them how to stave off wind & rain. Two others I set to work to quench the fire, because a part of the workshop had caught alight, and several great wooden windows were blazing like the devil, so that I was in terror lest the whole roof should be aflame, so tremendous was the fire. With the others, and there were plenty of them, I set to work clearing the channels, through which the metal was to run, and to opening all the vent holes. Scarce was this done when, all on a sudden, just as the work was being completed, owing to the terrific heat of the burning oak, the whole cap of the furnace was blown up into the air, and the metal began to well over on all sides; they stood in utter astonishment, all of them,—for they had obeyed me fearsomely—to see the caked metal thus again liquified. The strength of the fire, however, had consumed all the tin alloy, so I ordered to be thrown in a thick pig of fine pewter. When I saw this was of no avail, and that by God’s grace the metal was already beginning to flow & to spread itself on the sides of the furnace, I ordered two others to run into my house and fetch hither all my pewter plates and dishes, 200 lbs. weight in all, and threw them in bit by bit. Then I made another take iron crooks and strike out first one & then the second of the plugs, which were very hard. Then, as the metal began to flow through the channels, I, little by little, threw the thin pewter plates into it, which, owing to the immense heat, combined with the other pewter, so that my mould was soon filled. Seeing all this mass of metal run in so well without any bubbling or even a single hitch, I concluded that all my vents were doing their work. The amount of metal left over just corresponded exactly to the extra quantity thrown in, so that my mould was completely filled. When this was accomplished I gave thanks to God, and turning to the lot of them, said: ‘D’ye see how everything has its remedy?’ Spite of the pain such was my delight that I felt no more fatigue; the fever just went to the devil, & I sat down to eat and drink with a light heart, together with all the lot of them, and everyone marvelled thereat.