Notebook, 1993-

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

Second Section - (cont.)

On The Character of Ultramarine Blue, and How to make it.
Chapter LXII

Ultramarine blue is a color illustrious, beautiful, and most perfect, beyond all other colors; one could not say anything about it, or do anything with it, that its quality would not still surpass. And, because of its excellence, I want to discuss it at length, and to show you in detail how it is made. And pay close attention to this, for you will gain great honor and service from it. And let some of that color, combined with gold, which adorns all the works of our profession, whether on wall or on panel, shine forth in every object. [p. 36]

To begin with, get some lapis lazuli. And if you want to recognize the good stone, choose that which you see is richest in blue color, because it is all mixed like ashes. That which contains least of this ash color is the best. But see that it is not the azurite stone, which looks very lovely to the eye, and resembles an enamel. Pound it in a bronze mortar, covered up, so that it may not go off in dust; then put it on your porphyry slab, and work it up without water. Then take a covered sieve such as the druggists use for sifting drugs; and sift it, and pound it over again as you find necessary. And bear in mind that the more finely you work it up, the finer the blue will come out, but not so beautifully violet[57] in color. It is true that the fine kind is more useful to illuminators, and for making draperies with lights on them.[58] When you have this powder all ready, get six ounces of pine rosin from the druggists, three ounces of gum mastic, and three ounces of new wax, for each pound of lapis lazuli; put all these things into a new pipkin, and melt them up together. Then take a white linen cloth, and strain these things into a glazed washbasin. Then take a pound of the lapis lazuli powder, and mix it all up thoroughly, and make a plastic of it, all incorporated together. And have some linseed oil, and always keep your hands well greased with this oil, so as to be able to handle the plastic. You must keep this plastic for at least three days and three nights, working it over a little every day; and bear in mind that you may keep it in the plastic for two weeks or a month, or as long as you like. When you want to extract the blue from it, adopt this method. Make two sticks out of a stout rod, neither too thick nor too thin; and let them each be a foot long; and have them well [p. 37] rounded at the top and bottom, and nicely smoothed. And then have your plastic in the glazed washbasin where you have been keeping it; and put into it about a porringerful of lye, fairly warm; and with these two sticks, one in each hand, turn over and squeeze and knead this plastic, this way and that, just as you work over bread dough with your hand, in just the same way. When you have done this until you see that the lye is saturated with blue, draw it off into a glazed porringer. Then take as much lye again, and put it on to the plastic, and work it over with these sticks as before. When the lye has turned quite blue, put it into another glazed porringer, and put as much lye again on to the plastic, and press it out again in the usual way. And when the lye is quite blue, put it into another glazed porringer. And go on doing this for several days in the same way, until the plastic will no longer color the lye; and then throw it away, for it is no longer any good. Then arrange all these porringers in front of you on a table, in series: that is, the yields, first, second, third, fourth, arranged in succession; and with your hand stir up in each one the lye with the blue which, on account of the heaviness of this blue, will have gone to the bottom; and then you will learn the yields of the blue. Weigh the question of how many grades of blue you want: whether three or four, or six, or however many you want; bearing in mind that the first yields are the best, just as the first porringer is better than the second. And so, if you have eighteen porringers of the yields, and you wish to make three grades of blue, you take six of the porringers and mix them together, and reduce it to one porringer; and that will be one grade. And in the same way with the others. But bear in mind that if you have good lapis lazuli, the blue from the first two yields will be worth eight ducats an ounce. The last two yields are worse than ashes: therefore be prudent in your observation, so as not to spoil the first blues for the poor ones. And every day drain off the lye from the porringers, until the blues are dry. When they are perfectly dry, do them up in leather, or in bladders, or in purses, according to the divisions which you have. And know that if that lapis lazuli stone was not so very good, or if you worked the stone up so much that the blue did not come out violet, I will teach you how to give it a little color.[59] [p. 38] Take a bit of pounded kermes[60] and a little brazil;[61] cook them together; but either grate the brazil or scrape it with glass; and then cook them together with lye and a little rock alum; and when they boil you will see that it is a perfect crimson[62] color. Before you take the blue out of the porringer, but after it is quite dry of the lye, put a little of this kermes and brazil on it; and stir it all up well with your finger; and let it stand until it dries, without sun, fire, or wind. When you find that it is dry, put it in leather, or in a purse, and leave it alone, for it is good and perfect. And keep it to yourself, for it is an unusual ability to know how to make it properly. And know that making it is an occupation for pretty girls rather than for men; for they are always at home, and reliable, and they have more dainty hands. Just beware of old women. When you get around to wanting to use some of this blue, take as much of it as you need. And if you have draperies with lights on them[63] to execute, it ought to be worked up a little on the regular stone. And if you want it just for laying in, it wants to be worked over on the stone very, very lightly, always using perfectly clear water, and keeping the stone well washed and clean. And if the blue should get soiled in any way, take a little lye, or clear water; and put it into the dish, and stir it up well; and you will do this two or three times, and the blue will be purified entirely. I am not discussing its temperas for you, because I shall be showing you about all the temperas for all the colors later on, for panel, wall, iron, parchment, stone, and glass. [p. 39]



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