The IMLS (The Institute for Museum & Library Services) Project team is plugging along, cataloging, conserving, and rehousing artifacts from our collections storage building, as we mentioned in our blog a few months ago. Thus far we have worked on radios, phonographs, computers, adding machines, and their components. We have found some interesting objects in our collection, like this Motorola Radiophone, pictured above, ca 1950.
While conserving these objects from our storage facility, we are discovering cadmium corrosion on many objects, including the Radiophone. Cadmium is a bluish gray metal and was first used as a pigment (cadmium yellow, red, and orange) in paint, plastics, and glass. It was also used as a stabilizer in plastics, a component in batteries, and as a plating to prevent corrosion. Even though it is used to prevent corrosion of an underlying metal such as steel or aluminum a cadmium coating will corrode in the presence of organic acids, sulfur compounds, and atmospheric pollutants. Organic acids and sulfur compounds are emitted as a result of the deterioration of many materials from which objects in our collections are made, such as rubber, wood and the plastic cases of radios and phonographs. Cadmium corrosion products can range from brown to bright yellow. In our case, we are often finding plates, screws, brackets, and other plated metal components coated in bright yellow powdery cadmium sulfide corrosion.
The cadmium sulfide must be removed because it poses a health risk to those who may handle the objects in the future, and once the cadmium plating has been consumed by the corrosion process, the metal below will be susceptible to damage. Because of the toxicity and adverse long term health effects of cadmium exposure, we approached the task of its removal cautiously. In order to do this, our Collections Specialist and resident handyman Jacob Hildebrandt, devised a box akin to those used for sandblasting out of corrugated plastic, duct tape, and Plexiglas. This created a sealed space for corrosion removal. A small HEPA (High Efficiency Particulate Air) filter vacuum was also inserted into the box to collect loose cadmium products that could become airborne when opening the lid.
Once the object is placed inside the filtered box, the corrosion is removed with a fiberglass brush while utilizing the box’s interior gloves. To slow the formation of any further corrosion, the metal is coated with a 20% Acryloid B72 that has been dissolved in acetone and toluene.
By devising this method of mitigation for cadmium corrosion, we are keeping ourselves safe, as well as those who will come into contact with these objects in the future.
Cayla Osgood is a Conservation Specialist at The Henry Ford.
conservation, collections care, by Cayla Osgood, #Behind The Scenes @ The Henry Ford, IMLS grant
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