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
Milanesi [Chapter numbers]
CLXXI A Short Section on Operations with Glass: First, for Windows.
There are two processes for working on glass: that is, windows, and pieces of glass which are set in little anconas, or in embellishments for reliquaries. But we shall first discuss the method for windows. It is true that this occupation is not much practiced by our profession, and is practiced more by those who make a business of it. And ordinarily those masters who do the work possess more skill than draftsmanship, and they are almost forced to turn, for help on the drawing, to someone who possesses finished craftsmanship, that is, to one of all-round, good ability. And therefore, when they turn to you, you will adopt this method. He will come to you with the measurements of his window, the width and length: you will take as many sheets of paper glued together as you need for your windows; and you will draw your figure first with charcoal, then fix it with ink, with your figure completely shaded, exactly as you draw on panel. Then your glass master takes this drawing, and spreads it out on a large flat bench or table; and proceeds to cut his glasses, a section at a time, according to the way he wants the costumes of the figure painted. And he gives you a color which he makes from well-ground copper filings; and with this color, on the point of a minever brush, you shape up your shadows gradually, matching up the arrangement of the folds and the other details of the figure, on one piece of glass after another, just as the master has cut them and put them together; and you may shade any glass, indifferently, with this color. Then the master, before he fastens one piece to another, according to their practice, fires it moderately in iron cases with his ashes; and then he fastens them together.
You may execute silk stuffs, upon these glasses, sprig and hatch and do letting, that is, by laying in with this color, and then scraping through, just as you do on panel. You have one advantage: that you do not need to lay any other ground, because you can get glass in all colors.
And if you happen to have any very small figures to do, or arms or [p. 111] devices so tiny that the glasses could not be cut to shape, after you have shaded with the aforesaid color you may paint any costumes, and mark out with oil paint. And this need not be fired again, nor should that be done, for you would not accomplish anything. Just let it dry in the sun, as it will.
CLXXII How to Gild Glass for Reliquary Ornaments.
There is another process for working on glass, indescribably attractive, fine and unusual, and this is a branch of great piety, for the embellishment of holy reliquaries; and it calls for sure and ready draftsmanship. This process is carried out as follows. Take a piece of white glass, with no green cast, very clean, free from bubbles; and wash it, rubbing it down with lye and charcoal. And rinse it with good clear water, and let it dry by itself. But before you wash it, cut with a good clean whisk just as you do that for gliding, so that it is thoroughly beaten; and let it distill overnight. Then take a minever brush, and with this brush wet the back of the glass with this glair; and when it is thoroughly wet all over, take a leaf of the gold, which should be quite heavy gold, that is, dull; put it on the paper tip, and lay it deftly on the glass where you have wet it; and press it down with a little very clean cotton, gently, so that the glair does not get on top of the gold; and lay the whole glass in this way. Let it dry without sun for the space of some days.
CLXXII Arrangements for Drawing on This Glass.
When it is all dry, get a nice flat little panel, covered with black cloth or silk; and have a little study of your own, where no one will cause you any sort of interruption, and which has just one clothcovered window; and you will put your table in this window, as if for writing, so arranged that the window shines over your head when you have your face turned toward this window. With your glass laid out on this black cloth: [p. 112]
CLXXII How to Draw on the Gilded Glass.
Take a needle, fastened in a little stick as if it were a little brush, and have it quite sharp pointed. And, with the name of God, begin to draw lightly with this needle whatever figure you wish to make. And have this first drawing show very little, for it can never be erased; and therefore work lightly until you get your drawing settled; then proceed to work as if you were sketching with a pen, for this work has to be done freehand. And do you want to be convinced that you need to have a light hand, and that it should not be tired? -[Know] that the strongest shadow you can make consists in penetrating to the glass with the point of the needle, and no more; that the intermediate shadow consists in not piercing through the gold all over; that it is as delicate as that, and you must not work with haste--rather with great enjoyment and pleasure. And I give you this advice, that the day before the day you want to work at this job, you hold your hand to your neck, or in your bosom, so as to get it all unburdened of blood and weariness.
CLXXII How to Scrape the Gold off the Backgrounds.
When you have got your drawing finished, and you want to scrape away certain grounds, which generally want to be put in with ultramarine blue in oil, take a leaden style, and rub the gold, which it takes off for you neatly; and work carefully around the outlines of the figure. When you have done this:
CLXXII How to Back up the Drawing with Colors.
Take various colors ground in oil, such as ultramarine blue, black, verdigris, and lac; and if you want any drapery or lining to glisten [in lines of gold] on green, apply green; if you want it on lac, apply [p. 113] lac; if you want it on black, apply black. But the black is the most striking of all, for it shows up the figures better than any other color. [p. 114]
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