Cennino Cennini, "Il Libro dell' Arte" (15th century)

pp. 79-80 in Thompson translation
Another Way To Temper Bole on Panel, For Gilding.
Chapter CXXXII
This tempera can also be made in another way, in grinding the bole. Take the egg white and put it on the porphyry slab, whole, as it is. Then have the bole powered; wet it up in this egg white. Then grind it well and finely; and as it dries under your hands, add good clear clean water on the slab. Then when it is well ground, temper it with plain clear water, so that it runs from the brush; and lay four coats of it on your work in the same way described above. And this method will be surer for you than the other tempera as long as you have not had much experience. Cover up your ancona carefully, and protect it from dust, as I have said.

pp. 80 in Thompson translation
How You May Gild on Panel With Terre-Verte.
Chapter CXXXIII
You may do also as our forefathers used to, that is, apply canvas all over the whole ancona before you gesso; and then gild with terre-verte, grinding this terre-verte with whichever of these two kinds of tempera, which i have just taught you, you prefer.

pp. 80-82 in Thompson translation
How To Gild On Panel.
Chapter CXXXIIII
When some mild damp weather comes along, and you want to do some gilding, have this ancona laid out on two trestles. Take your feathers; sweep it off thoroughly. Take a little hook feel over the ground of the bole with a light touch. If there should be any foreign matter, or any any little lump or grit, get rid of it. Take a piece of a strip of linen cloth, and burnish the bole briskly. Burnishing it also with a crook [stone burnisher with a curved point] would be sure to help When you have got it burnished and cleaned up in this way, take a goblet almost full of good clean clear water, and put a little of that white-of-egg tempera into it. And if it were a trifle stale, so much the better. Mix it up thoroughly with the water in the goblet. Take a good-seized minever brush made out of the tips of the tails as I told you before; take your fine gold, and pick up the leaf carefully with a pair of tweezers or small pincers. Have a card cut in a square larger than the leaf of fold, trimmed off at each corner Hold it in your left hand and, using the brush with your right hand, wet down as much of the bole as is to receive the leaf of gold which you have in your hand. And wet it down evenly, so that there will not be any more water in one place than in another. Then carefully bring the fold up to the water on the bole; but have the gold extend a little bit beyond the card, just so that the little time of the card will not get wet. Now, as soon as you have brought the gold into contact with the water, instantly and quickly draw your hand and the little tip toward you. And if you observe that the gold is not all in contact with the water, take a bit of fresh cotton-wool, and tamp the gold down, as lightly as ever you can. And lay some more leaves in the same way. And when you are wetting down for the second leaf, take care to run the brush along the edge of the leaf just laid so accurately that the water will not run over it. And see to it that you lap the one which you are laying a little bit over the one which has been laid; first breathing upon the latter, so that the gold will adhere to the part where it overlaps. When you have laid about three pieces, go back and tamp the first one down with the cotton, breathing on it, and that will show you whether it requires any faulting. Then fix yourself up a cushion, the size of a brick or tile, that is, a good flat board, with some nice soft while leather with hearings. Then lay a leaf of gold out flat on this cushion; and with a good straight spatula cut this gold into such little pieces as you require for the faults which remain. Take a small pointed minever brush, and wet these faults with the usual tempera. And thus, if you moisten the handle of the bush with your lips a little cupped, it will be adequate to pick up the little scraps of gold and lay it on the fault. When you have finished the flats, though you ought to lay it so that you can burnish it the same way, as I shall show you when you have to gil moldings or leaves, take pains to gather up the caps, as the master does who wishes to pave his way; so that you may always be as thrifty with the gold as you can, and make economies with it; and over up the gold which you have laid, with white napkins.