A conservator should be able to make his own cleaning agents and thus know what materials are being used, says Wolbers.
There’s no reason for following a recipe blindly and not knowing what we are doing in essence. When a conservator knows what is available, how to customize it, and what ingredients work for a specific case, a deliberated cleaning system can be selected.
Alternative methods for cleaning painted surfaces
In the 1980s, Professor Richard Wolbers developed alternative methods for the cleaning of painted surfaces. His innovative approaches consist of utilizing specific aqueous methods (enzymatic digestions, chelation, acid-base chemistry and tailored solvent-surfactant systems) to aid in the removal of non-original coatings or retouches. When thickened, these water-based or solvent-based systems provide more control during cleaning, in contrast to the application of free solvents. Also, they are favorable for the removal of complex layers and can solubilize a wide range of materials. Furthermore, these systems can be formulated to unpack specific layers while leaving others layers intact. These cleaning systems can be tailored to remove a specific layer, however, this new approach to cleaning requires some knowledge about the paint composition of the object and the layer(s) to be removed. Professor Wolbers still teaches several workshops on these methods for conservators around the world. In 2000, he published Cleaning Painted Surfaces: Aqueous Methods which discusses cleaning materials such as surfactants, enzymes, and pH-adjusted aqueous solutions, and provides information about the chemistry of gel components
Wolbers cleaning systems are not yet part of everyday conservation practice
His cleaning systems could resolve problematic cases, however, they are not yet entirely integrated into everyday practice in private and public conservation studios. Possibly this is due to the level of chemistry required for successful application of these methods, as well as the ever-changing and constant development of new materials within the chemical industry. Also, Wolbers does not want to provide ‘cure-all’ recipes, but rather offer a new methodology with which to manipulate and apply various cleaning components. His philosophy that “a conservator should be able to make his own cleaning agents and thus know what materials are being used,” is an ambitious philosophy which requires chemical understanding and insight.
Considerations pointed out
Therefore two short case studies are presented in this presentation to offer different examples of how gels were successfully applied to the cleaning of historic interiors.
These case studies examine the considerations necessary before selecting a cleaning gel and describe a customized solvent gel specific to each artwork and serve as individual examples of the manner in which these gels can be prepared and applied. Also the chemistry of the ingredients used to make the solvent-based cleaning gels from each treatment will be explained.
This is an abstract of the presentation during the Joint Meeting in oktober 2012, by W. van der Sar, based on her MA-thesis at the University of Amsterdam (department Conservering & Restauratie) and an internship at the department in Winterthur