Camille Polkownik

This study explores the difficulties associated with analysing Prussian blue, and the extenders associated with it, as an early synthetic pigment. A selection of samples from paintings by Canaletto and other eighteenth-century Italian artists were analysed to produce a survey of elements found in early Prussian blue and a tentative characterisation of extenders used in association with this pigment.

Abstract
Prismatic lead white was first described by Walter C. McCrone in 1983 when it was identified via polarised light microscopy in three paintings by Edouard Manet. It is characterised by crystals in the shape of bullets or pills (i.e. prism-shaped, hence ‘prismatic lead white’). McCrone attributed the formation of these crystals, morphologically distinct from those of ‘normal’ lead white, to processing conditions characteristic of precipitated lead white. These ‘prismatic’ crystals have subsequently been identified as cerussite (orthorhombic lead carbonate, PbCO3). Their presence has been tentatively used to date artworks painted from the nineteenth century onwards. The article will show, through reproducing historic pigment recipes of post-treatments, that prismatic lead white can also be formed in the stack lead white process and so its presence should not be used as a criterion for dating. This article investigates the formation of these prismatic crystals in the context of the manufacture and history of lead white.

Abstract David Parr House, situated at 186 Gwydir Street in Cambridge, is the former home of the decorative painter David Parr. The house is extensively decorated and the rooms are embellished with a variety of
Victorian and early twentieth-century decorative patterns. This article concentrates on the two main rooms:
the Drawing Room and the Dining Room, and focuses on the technical study of the materials and techniques
employed by Parr. The findings of the study are placed within the context of artists’ materials and practice at
the turn of the century, thereby relating Parr’s own artistic process with the public art sphere of this period.

Abstract Traditionally, different qualities of lead white were available to artists depending on their location
and budget. After its synthesis, lead white was refined through post-synthesis treatments such as washing
in water or vinegar, heating and bleaching. It is now known that these treatments altered the crystalline
structure of the material, but whether they influenced the handling and optical properties of the pigment is
unknown. Studies investigating the ratios of the different phases comprising the pigment have found that
the ratios varied, sometimes wildly, within the same work of art. This study focuses on the handling and
specific optical properties of lead white pigments with different phase ratios. Historical recipes have been
reconstructed, including post-synthesis treatments, and the materials tested to observe any changes in handling and optical properties in order to understand the reasons why artists bought certain qualities of lead
white to paint specific areas.

Modern and contemporary art have brought changes
to conservation theories and ethics. Synthetic and
unconventional materials used to make contemporary
artworks are often sensitive to their environment, and do not
stand up well to the test of time. Unlike the Old Masters, who
knew their pigments and mediums intimately, most of today’s
artists are not aware of the poor aging of materials, or their
potential interactions which can provoke premature aging and
degradation. Furthermore, this aging damages the aesthetic
of the artwork and subsequently alters or distorts the initial
meaning and intent of the artist. English artist Damien Hirst
(born 1965) himself said: “Are you looking for the original
object, is that what you want to preserve, or do you want to
communicate the idea that was originally intended (PPRA
King and Bracker, 2015)?” Two cases studies that illustrate
particular issues faced by conservators will be introduced and
the conservation processes will be discussed. Finally, the use
of replicas as a potential solution will be examined.

La triéthanolamine est l’un des ingrédients principaux des savons résiniques et biliaires. Elle présente un mauvais vieillissement (jaunissement) ainsi qu’une affinité avec la couche huileuse des peintures, laissant des résidus après utilisation. Il est donc intéressant de comprendre comment fonctionnent ces savons de façon à remplacer cet ingrédient problématique par des substituts facilement accessibles aux restaurateurs.

Le travail présenté dans cet article a été réalisé par l’auteur lors de son Master 2 en conservation et restauration de peintures à la Cambre. Une brève introduction des savons sera faite, puis leurs principales utilisations, ainsi que leur composition et fonctionnement seront expliqués. Ensuite, la polémique autour de ces produits sera résumée et permettra d’introduire la partie pratique, dans laquelle les nombreux essais réalisés dans le but de remplacer l’un des ingrédients principaux du savon supposé problématique seront présentés.