Using Electrolysis on Metal Artifacts found at the Kooskia Internment Camp

Hello there, my name is Brian Schneider and I am a Master’s Candidate at the University of Idaho. My main interests in archaeology go all the way over to the east coast where I focus on the archaeology of slavery, and particularly landscape studies dealing with the utilization of space. While my interest in history predates the Kooskia Internment Camp my research still intersects with that of the Kooskia project. While I am interested in looking at whether the internees were repurposing metal items (particularly machine parts) for their own purposes, I am also involved in creating an electrolytic reduction apparatus or electrolysis machine.

Figure 1: Horseshoe found at the Kooskia Internment Camp

Electrolysis is a process where corrosion is removed from metal objects by passing an electric current through the metal artifacts. This can be a touchy project depending on what metal the artifact is made up of. Most of my experience has been conserving ferrous metals (such as this horseshoe from the Kooskia Internment Project in Fig. 1). Electrolysis is useful in cases where metals are too corroded to get a clear picture of what the artifact was or how it may have been utilized (Fig. 2). There are two types of electrolytic reduction: 1) low amperage, used for cast and pig iron, and 2) high amperage, which is reserved for wrought iron. In both cases the apparatus is the same; it is merely the power of the current being passed through the artifact.

Figure 2: Ferrous Metal Artifact from the Kooskia Internment Camp

The apparatus used in electrolysis is as follows: a charger is used to provide the amperage with several alligator clips attached to positive and negative terminals. These terminals are a steel mesh or other steel item acting as the positive (+) terminal (for iron, for copper the anode should also be of copper (Rodgers 2004:114)) and the artifact or artifacts as the negative (-) terminal.  The artifact is set into a stainless steel tank filled with a solution of distilled water and baking soda. What this does is turn the corrosive agents into hydrogen gas without affecting the carbonized surface of the artifacts. The lower amperage method should present the least damage to the artifact itself.

Once the electrolysis is complete the artifact needs to be stabilized. For all artifacts this includes a rinse in distilled water for several hours, allowing the baking soda and distilled water to be removed. For iron objects, there are two more steps to ensure the conservation of the artifact.  The dehydration method allows the artifact to be cleansed moisture still present. There are two method; the first is baking the artifact, which is useful if there is nothing decorative still attached. The second is solvent dehydration. This uses either denatured alcohol or acetone (Rodgers 2004:94) and works similar to baking. This is better for more sensitive artifacts such as those with paint still attached or some other delicate design. Once this has been completed, a final sealing coat is placed on the artifacts; either wax or shellac can be used. This serves as a humidity barrier to ensure that the artifact will remain safe. The process is similar for other metals, although some, like silver, may not need a protective coating.

So that is the electrolytic reduction process in a nutshell. I am looking forward to creating this machine, because there are some pretty interesting metal artifacts that were recovered. By conserving and cleaning them up, we can get a better idea of what these artifacts were and how they might have been used.

References

Rodgers, Bradley A. The Archaeologist’s Manual for Conservation: A Guide to Non-Toxic, Minimal Intervention Artifact Stabilization, Kluwer Academic/Plenum Publishers, New York, 2004.


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