"Have a glove on your left hand: and first grind some vine-sprig black*, ground very fine with water, then thoroughly dried either by sun or fire, then ground again, dry; and mix it with as much liquid varnish as may be required; and take up some of this black with a little trowel, and spread it out on the palm of your hand, that is, on the glove. And thus you ink up the block with it where it has been engraved, neatly, so that the incision does not get choked up."
*"Then take a portion of this black, or of any other colour, the size of a nut; put it on this stone, and with the one which you hold in your hand crush this black up thoroughly. Then take some clear river or fountain or well water, and grind this black for the space of half an hour, or an hour, or as long as you like; but know that if you were to work it up for a year it would be so much the blacker and better a colour."
The Craftsman's Handbook of Cennino d'Andrea Cennini 15th C.
trans. D. V. Thompson Jr. 1960