Presented by Dr. Bill Wei, Senior Conservation Scientist of Netherlands Institute for Cultural Heritage, and representing work by others cited in the program
Dr. Wei presented primer on electrocleaning and he notes the he stumbled into this project. Part of project on Objects in Context – cleaning and perception.
This project uses case studies over the next four years to find out what is acceptable and what is readable? Dr. Wei has been looking at paintings, photographs and outdoor sculpture.
General philosophy – bring conservators and art historians and scientist together to collaborate.
Electrochemical cleaning – brief summary presented including simplified explanation of reduction and oxidation. Interesting diagram showed PT as the wand rather than Ag. Electrolyte selection and level of conductivity (potential) is key. Potential = Current x Resistance. With daguerreotype one moves the potential but in industry variable is current density. “Pen” can be used. Allows one to control the cleaning rate at a safe potential. Allows one to work locally. Distance is another variable.
Can this (electrolytic cleaning) be controlled? Yes. Note differences between simple metal and daguerreotype are more complex. Gold layer is not continuous. Mixed electrode.
CONCLUSIONS:
Not saying he is “for” this method of cleaning but trying to make it less mysterious.
Examination of silver tarnish – using sterling silver plates that were exposed to barium sulfate. Looked at different cathodic potentials.
Examination on original plate. -1.3volts potential used. PT electrode. (Note these are very expensive.) Change in larger particles under magnification – they are present but broken up. These may be oxide particles. This is simply a proof of concept. Image is more readable and no major change to surface.
Additional research required. Are there copper deposits on the surface? Silver deposits? What is the significance of the degradation of the larger particles under magnification – this research will continue and focus beyond electrochemical and using a variety of techniques.
Ethical question of cleaning not addressed but we must all consider and be well versed in conservation theory as presented during our (excellent) general sessions.
Restoration ethics – perception and readability – all key. Blind perception testing will ensue using different methods for evaluation by conservators.
In terms of future research keep in mind the potential presence of coatings. Dr. Susan Barger examined the micrographs presented in the talk (from an image purchased on EBay) and explained that this is a not-so-good daguerreotype owing to variety of particles that are not well formed. She further noted that etching visible may be from cyanide cleaning. Will further examine vertical and horizontal cleaning.