When you want to lay a gesso ground on panels, and they are large and numerous, boil some skins to make some fresh glue as we have directed, as old glue loses its power when it is left too long before being applied to panels. If you are in a hurry and there are only a few panels, do thus: break up some dried glue into small pieces and put them to soak in water overnight in an earthernware pot or some other vessel put in a cool place so that it does not deteriorate. Then put it on to boil, stirring with a stick until it is dissolved; take off as much glue as will be sufficient for the panels that you have, add water to dilute it, and give them a thin coat of it. See that the glue does not form a shiny surface on the panels, and do not let bubbles form, but let it be absorbed by the wood. If there is some sun, put the panels in it so that this first layer can dry out; later on, do not do this as the gesso will flake off. After the panels are properly dried out, mix some gypsum with good glue in a quantity sufficient to put on five or six layers, and test it out on a small board. If it is too brittle add gypsum and hot water to soften it; if it is too soft add more glue until it is at its right consistency, and so treat the panels with their second and third layers; for the fourth add some peziri (6) and a very little soap and finish by applying the other two or three layers. Take care not to be in a hurry and put on a thick layer of gesso in order to prepare the panels quickly, as when you come to rub it down the first layer will separate from the second and the image will be uneven. So apply the gesso in very thin layers, making a number of them to give a good ground. If it is summer, and you are afraid of making the gesso porous, make a strong glue and strain it, putting it in a cool place to stand; when you want to lay a gesso ground mix up a little of the glue, as much as you think will be sufficient to finish one layer, and apply it; do this again with just as much as you want to complete the second layer of gesso, and for the next layer add just as much again, and so on until you have finished, and in this way you will avoid having bubbles. If you leave the glue standing too long with the gypsum, it will be spoilt. Then you rub it down, draw on it and gild it.,,Commentary Hetherington: (6) Peziri must refer to one of the drying oils. Although the oil from walnuts or poppy-seed could have been in use, it is most probably to linseed oil that Dionysius is referring