Il Libro dell' Arte - Cennino D' Andrea Cennini. The Craftsman's Handbook. The Italian "Il Libro dell' Arte." Translated by Daniel V. Thompson, Jr. New York: Dover Publications, Inc. 1933, by Yale University Press.
Notes 1-50 Notes 51-124 Notes 125-162 Notes 163-283
See that the wood is thoroughly dry; and if it were wooden figures, or leaves, so that you could boil them with clear water in kettles, that wood would never give you any trouble with cracks.
Let us just go back to the knots or nodes, or other defects which the flat of the panel may display. Take some strong leaf glue; heat up as much as a goblet or glass of water; and boil two leaves of glue, in a pipkin free from grease. Then have some sawdust wet down with this glue in a porringer. Fill the flaws of the nodes with it, and smooth down with a wooden slice, and let it stand. Then scrape with a knife point until it is even with the surrounding level. Look it over again; if there is a bud, or nail, or nail end, sticking through the surface, beat it well down into the board. Then take small pieces of tin f oil, like little coins, and some glue, and cover over carefully wherever any iron comes; and this is done so that the rust from the iron may never come to the surface of the gessos. And the flat of the ancona must never be too much smoothed down. First take a size made of clippings of sheep parchments, boiled until one part remains out of three. Test it with the palms of your hands; and when you find that one palm sticks to the other, it will be right. Strain it two or three times. Then take a casserole half full of this size, and the third [part] water, and get it boiling hot. Then apply this size to your ancona, over foliage ornaments, canopies, little columns, or any sort of work which you have to gesso, using a large soft bristle brush. Then let it dry. [p. 69] Next take some of your original strong size, and put two coats over this work with your brush; and always let it dry between one coat and the next; and it will come out perfectly sized. And do you know what the first size, with water, accomplishes? Not being so strong, it is just as if you were fasting, and ate a handful of sweetmeats, and drank a glass of good wine, which is an inducement for you to eat your dinner. So it is with this size: it is a means of giving the wood a taste for receiving the coats of size and gesso.
How You Should Put Cloth on a Panel.
When you have done the sizing, take some canvas, that is, some old thin linen cloth, white threaded, without a spot of any grease. Take your best size; cut or tear large or small strips of this canvas; sop them in this size; spread them out over the flats of these anconas with your hands; and first remove the seams; and flatten them out well with the palms of your hands; and let them dry for two days. And know that this sizing and gessoing call for dry and windy weather. Size wants to be stronger in summer than in winter. Gilding calls for damp and rainy weather.
How the Flat or a Panel Should be Gessoed With the Slice with Gesso Grosso.
When the ancona is quite dry, take a tip of a knife shaped like a spatula, so that it will scrape well; and go over the flat. If you find any little lump, or seam of any sort, remove it. Then take some gesso grosso, that is, plaster of Paris, which has been purified and sifted [p. 70] like flour. Put a little porringerful on the porphyry slab, and grind it with this size very vigorously, as if it were a color. Then scrape it up with a slice; put it on the flat of the ancona, and proceed to cover all the flats with it, with a very even and rather broad slice; and wherever you can lay it with this slice you do so. Then take some of this same ground-up gesso; warm it; and take a small soft bristle brush, and lay some of this gesso over the moldings and over the leaves, and likewise over the flats gessoed with the slice. You lay three or four coats of it on the other parts and moldings; but you cannot lay too much on the flats. Let it dry for two or three days. Then take this iron spatula and scrape over the flat. Have some little tools made which are called "little hooks," such as you will see at the painters' made up in various styles. Shape up the moldings and foliage ornaments nicely, so that they do not stay choked up; get them even; and contrive to get every flaw in the flats and gap in the moldings repaired by this gessoing.
How to Make the Gesso Sottile or Gessoing Panels.
Now you have to have a gesso which is called gesso sottile; and it is some of this same gesso, but it is purified for a whole month by being soaked in a bucket. Stir up the water every day, so that it practically rots away, and every ray of heat goes out of it, and it will come out as soft as silk. Then the water is poured off, and it is made up into loaves, and allowed to dry; and then this gesso is sold to us painters by the apothecaries. And this gesso is used for gessoing, for gilding, for doing reliefs, and making handsome things. [p. 71]
How to Gesso an Ancona with Gesso Sottile; and How to Temper it.
When you have done the gessoing with gesso grosso, and scraped it nice and smooth, and evened it up well and carefully, take some of this gesso sottile. Put it, loaf by loaf, into a washbasin of clear water; let it soak up as much water as it will. Then put it on the porphyry slab, a little at a time, and without putting any more water in with it, grind it very thoroughly. Then place it neatly on a piece of strong white linen cloth; and keep on doing this until you have taken out one loaf of it. Then fold it up in this cloth, and squeeze it out thoroughly, so as to get as much water out of it as possible. When you have ground as much of it as you are going to need, which you must consider carefully, so as not to have to make gessos tempered in two ways, which would not be a good system, take some of that same size with which you tempered the gesso grosso. Enough of it wants to be made at one time for you to temper the gesso sottile and the grosso. And the gesso sottile wants to be tempered less than the gesso grosso. The reason? -Because the gesso grosso is your foundation for everything. Nevertheless, you will naturally realize that you cannot squeeze the gesso out so much that there will not still be some little water left in it. And for this reason, make the same size, confidently.
Take a new casserole, which is not greasy; and if it is glazed, so much the better. Take the loaf of this gesso, and with a penknife cut it thin, as if you were cutting cheese; and put it into this casserole. Then pour some of the size over it; and proceed to break up this gesso with your hand, as if you were making a batter for pancakes, smoothly and deftly, so that you do not get it frothy. Then have a kettle of water, and get it quite hot, and place this casserole of tempered gesso over it. And this keeps the gesso warm for you; and do not let it boil, for if it boiled it would be ruined. When it is warm, take your ancona; and dip into this pipkin with a good-sized and quite soft bristle brush, and pick up a reasonable amount of it, neither lavish nor skimpy; and lay a coat of it all over the flats and moldings and foliage ornaments. It is true that for this first coat, as you are applying it, you smooth out and rub over the gesso, wherever [p. 73] you lay it, using your fingers and the palm of your hand, with a rotary motion; and this makes the gesso sottile unite well with the grosso. When you have got this done, begin over again, and apply a brush coat of it all over, without rubbing it with your hand any more. Then let it stand a while, not long enough for it to dry out altogether; and put on another coat, in the other direction, still with the brush; and let it stand as usual. Then give it another coat in the other direction. And in this way, always keeping your gesso warm, you lay at least eight coats of it on the flats. You may do with less on the foliage ornaments and other reliefs; but you cannot put too much of it on the flats. This is because of the scraping which comes next.
How You May Gesso with Gesso Sottile Without Having Gessoed with Gesso Grosso First.
Furthermore, it is all right to give any small-sized and choice bits of work two or three coats of size, as I told you before; and simply put on as many coats of gesso sottile as you find by experience are needed.
How You Should Temper and Grind Gesso Sottile for Modeling.
How You Should Start to Scrape down an Ancona Flat Gessoed with Gesso Sottile.
When you have finished the gessoing, which must be finished in one day [and, if necessary, put in part of the night at it, just so you allow your required intervals], let it dry without sun for at least two days and two nights: the longer you let it dry, the better it is. Take a rag and some ground-up charcoal, done up like a little ball, and dust over the gesso of this ancona. Then with a bunch of hen or goose feathers sweep and spread out this black powder over the gesso. This is because the flat cannot be scraped down too perfectly; and, since the tool with which you scrape the gesso has a straight edge, wherever you take any off it will be as white as milk. Then you will see clearly where it is still necessary to scrape it down.
How the Gesso Sottile on the Flats Should be Scraped Down, and What These Scrapings are Good for.
First take a "little hook" with a straight edge, one finger wide, and go lightly all around the flat, scraping the molding once. Then take your spatula, ground to as straight an edge as possible; and with a light touch, not holding the point tightly at all, you rub it over the flat of your ancona, sweeping the gesso ahead of you with these feathers. And know that these sweepings are excellent for taking the oil out of the parchments of books. And in the same way scrape down the moldings and foliage ornaments with your little tools; and smooth it up as if it were an ivory. And sometimes, if you are hurried and have several jobs on hand, you may just smooth up the moldings and foliage ornaments with a linen rag, soaked and wrung out, rubbing it well over these moldings and foliage ornaments. [p. 74]
How to Draw on Panel. With Charcoal, to Begin with, and to Fix it with Ink.
When the gesso has all been scraped down, and come out like ivory, the first thing for you to do is to draw in your ancona or panel with those willow coals which I taught you to make before. But the charcoal wants to be tied to a little cane or stick, so that it comes some distance from the figures; for it is a great help to you in composing. And keep a feather handy; so that, if you are not satisfied with any stroke, you may erase it with the barbs of the feather, and draw it over again. And draw with a light touch. And then shade the folds and the faces, as you did with the brush, or as you did with the pen; for you draw as if you were working with a pen. When you have finished drawing your figure, especially if it is in a very valuable ancona, so that you are counting on profit and reputation from it, leave it alone for a few days, going back to it now and then to look it over and improve it wherever it still needs something. When it seems to you about right [and bear in mind that you may copy and examine things done by other good masters; that it is no shame to you], when the figure is satisfactory, take the feather and rub it over the drawing very lightly, until the drawing is practically effaced; though not so much but that you may still make out your strokes. And take a little dish half full of fresh water, and a few drops of ink; and reinforce your whole drawing, with a small pointed minever brush. Then take a little bunch of feathers, and sweep the whole drawing free of charcoal. Then take a wash of this ink, and, with a rather blunt minever brush, shade in some of the folds, and some of the shadow on the face. And you come out with such a handsome drawing, in this way, that you will make everyone fall in love with your productions. [p. 75]
How You Should Mark out the Outlines of The Figures for Gilding the Grounds.
When you have got our whole ancona drawn in, take a needle mounted in a little stick; and scratch over the outlines of the figure against the grounds which you have to gild, and the ornaments which are to be made for the figures, and any special draperies which are to be made of cloth of gold.
How to Model on a Panel with Gesso Sottile, and How to Mount Precious Stones.
After this, take some of that gesso for modeling, if you want to model any ornament or foliage ornament, or to mount any precious stones in any special ornaments in front of God the Father or Our Lady, or any other special embellishments, for they add greatly to the beauty of your work. And there are glass gems of various colors. Arrange them systematically, and have your gesso in a little dish over a pot of hot ashes, and a little dish of hot clear water, for you have to wash the brush out often; and this brush is to be of minever, quite fine, and rather long; taking up some of the warm gesso neatly on the tip of this brush; ; and briskly set to modeling whatever you please. And if you are modeling any little leaves, draw them in first, as you do the figure. And do not try to model many of them, or too many complicated objects; for the clearer you make your foliage ornaments, the better they respond to the stamping with the rosette, and they can be burnished better with the stone. There are some masters who, after they have modeled what they want, apply one or two coats of the gesso with which they gessoed the ancona, just the gesso sottile, with a soft bristle brush. But if you model lightly, in my opinion you get a finer, stronger, surer result by not putting any on, by the system which I stated earlier--of not putting on several types of gesso temperas. [p. 76]
How you Should Cast a Relief for Embellishing Areas of Anconas.
Since we are on the subject of modeling, I will tell you something about it. With this same gesso, or some stronger of size, you may cast a lion's head, or any other impressions taken in earth or in clay. Oil this impression with lamp oil; put in some of this gesso, well tempered; and let it get quite cold; and then lift up the gesso at the side of the impression, with the point of a penknife, and blow hard. It will come out clean. Let it dry. Then apply some in embellishments in this way. With a brush, smear some of the same gesso with which you do the gessoing, or some of that with which you model, wherever you want to put this head; press it down with your finger, and it will stay in place neatly. Then take some of this gesso, and lay a coat or two of it, with the minever brush, over the part which you are modeling, and rub over this casting with your finger; and let it stand. Then feel over it with a knife point, to see whether there are any little lumps on it, and remove them.
How to Plaster Reliefs on a Wall.
I will also tell you about modeling on a wall. In the first place, there are certain wall jobs involving curves or leaves which cannot be plastered with the trowel. Take some well-sifted lime, and well-sifted sand; put them into a pan, and temper them well to a batter, with a large bristle brush and clear water; and apply several coats of it with this brush to the places in question. Then smooth it with the trowel, and it will come out neatly plastered. And execute it, wet and dry, as you were taught for work in fresco. [p. 77]
How to Model with Mortar on a Wall the Way You Model with Gesso on Panel.
Furthermore, with the aforesaid mortar, worked up a little on the stone, you can model whatever you want on a wall, just the way I taught you for panel, right in the mortar and fresh plaster.
How to Take Reliefs from a Stone Mold, and How They are Good on Wall and on Panel.
You may also get a stone, carved with devices of any style you wish; and grease this stone with bacon fat or lard. Then get some tin foil; and, laying some fairly moist tow on the tin which lies over the mold, and beating it as hard as you can, with a willow mallet, you then take gesso grosso ground with size, and fill up this impression with the slice. You may embellish with these on a wall, on chests, on stone, on anything you please, afterward putting some mordant over the tin; and when it is a little tacky, gild it with fine gold. Then, when it is dry, fasten it to the wall with ship pitch.
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