Above: Evangelist Luke, From the Morgan Gospels, Northeast France, second half of the 9th century, 9 5/8 x 8 1/4 in. (24.5 x 21 cm), The Pierpont Morgan Library, New York. Purchase by John Pierpont Morgan, Jr., 1919. MS M. 640; Evangelist Matthew, From the Arenberg Gospels, Canterbury, England, ca. 1000???1020, The Pierpont Morgan Library, New York, M. 869.
One point that I???ve emphasized in the exhibition is that though we normally think of drawing as a preparatory exercise???a way to explore an idea or map out a composition???medieval artists and patrons, particularly in the early Middle Ages, often thought of drawing as a finished product, worthy of important and luxury books. Some artists even made use of gold to embellish their drawings. Though it wasn???t my intent, the exhibition provides a nice survey of gilding techniques.
When installing the exhibition, I fell into a discussion with conservators from the Morgan Library and from the Met over the strange green-gold that appears in the Morgan Gospels. You see it on the halo, the lectern, and the footstool in the image of Saint Luke writing his gospel (above left). We had noted the same pigment in the illuminations of other early books, and one of the conservators recalled some medieval recipes for gold paint that combine gold with verdigris, the green coating or patina formed when copper is exposed to air.
A medieval source called the Mappae clavicula includes the following recipes:
Mix 2 parts of gold powder and 1 part of verdigris with the composition [binding agent]; mix it again and make use of it as you wish.
Take very clean copper leaf and hang it over very sharp vinegar. Leave it undisturbed in the sun for 14 days. Open it up, take away the leaf, and collect the efflorescence, and you will make the cleanest verdigris.
Another better-known and more frequently used method of gilding involved the application of gold leaf, whereby thin sheets of gold are laid down on a binding medium applied to the page. The portrait of Matthew from the Arenberg Gospels (above right) provides a marvelous instance of drawing mixed with gold leaf. I particularly love how the pages of the book held by Matthew were deemed worthy of gilding.
A few days ago, a visitor to the exhibition approached me to ask about the raised and impressively shiny gold letters in the Tickhill Psalter. In that instance, gesso was used as the binding medium to give added height and to create an ideal surface for burnishing. In the case of the unfinished pages of the Prato Haggadah, the pink Hebrew letters that we see are the result of a colorant added both to make the binding agent more visible and to enrich the tonality of the gold leaf that, had the pages been completed, eventually would have been added.