Background Research

The objective of this component has been to obtain and tabulate the basic information on the historical primary sources dealing with organic materials in wall paintings and on recent analytical studies and identification of organic materials.

Primary Sources
The historical literature was reviewed, looking at the types of organic materials used in wall paintings as described in manuscripts, treatises, and manuals. The objective of the historical review was to identify and collect references on the typology and use of organic materials. The review focused on literature addressing western European lime-based wall paintings from the late medieval period to the eighteenth century. Historical sources such as manuscripts, treatises, and manuals that describe the methods and materials for painting on walls provided interesting insights into the variety of organic materials, including pigments, used by artisans over the course of centuries.

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A total of 231 recipes were reviewed and 16 general classes of organic constituent were identified, including beer, wine, vinegar, egg (egg white and yolk), gall, glues, flour and starch, oils, gums, resins, varnishes, waxes, milk, sugar, vegetable products, and human metabolic products. Around 60 recipes addressed gilding methods, describing the preparation of glue for metal foil, its use as a varnish to imitate the color gold or as a protective coating for gold, silver, and tin foils. The classifications are not meant to represent a scientific nomenclature, but rather a simple way to group recipes through their ingredients as cited in the manuscripts. All these recipes are organized in a ProCite® database at the GCI. Whenever possible the reference is given to a text that includes the recipe in English. When available, the recipe in the original language is also included in the database.

Analytical Literature
The review of the analytical literature was carried out to determine which types of organic materials have been identified in wall paintings and which analytical techniques used for this purpose. To achieve this goal, analytical literature on wall paintings studies from 1960 to 2002 was reviewed. References to organic materials identification in historic wall paintings were organized according to the analytical technique used to determine the presence of organic materials. Approximately 60 references have been identified and the information is stored in an Access® database at the GCI, where references are organized by author, date, type and period of the wall painting studied, techniques used, and type/class of organic materials found.

Cataloging of the Tintori Wall Painting Replica Samples
Throughout his professional life, the late Leonetto Tintori at the Laboratorio per l'Affresco di Elena e Leonetto Tintori was interested in and studied the presence and the role of organic materials in wall paintings. In his extensive career as a wall painting conservator, Tintori had constant reminders of the need for understanding the presence and the role of these materials for the appropriate preservation of wall paintings. He concentrated his work on this subject beginning in 1983 when he created a center at his house in Vainella near Prato, Italy, to study these problems and to teach wall paintings techniques.

In pursuit of this interest, Tintori made hundreds of wall paintings replicas simulating different techniques and material combinations. The replicas are painted in sectors—i.e., an area completely covered with the same painting technique and phase of application. Used in these sectors were organic materials such as egg, oil, casein, and milk, in combination with different types of pigments and mortars. Tintori documented each replica in terms of the materials and methods used and, in some instances, the relative amounts of the binders and pigments used. As part of the OMWP project, these replicas were catalogued in an Access® database that will allow for identifying sectors by binder, pigment, and phase of application.

Last updated: March 2011