Take a moment to watch the small bubbles coming off the metal artifacts inside this tank.  

 

You’re witnessing an electrical and chemical reaction that converts rust and other corrosion products into a more stable form.  

 

Electrolysis, or electrolytic reduction, is an electrochemical process that can be harnessed to clean and conserve corroded archaeological material. 

 

The process involves passing direct electrical current through an ionic solution where archaeological metals connected to a negative electrical current serve as cathodes, and sacrificial metals connected to a positive electrical current, such as the pieces of threaded steel rebar at the edges of this tank, serve as the electron donors or anodes. 

 

The direct current establishes a galvanic circuit in which negatively-charged chloride ions are attracted from the artifacts to the sacrificial metals, thus purging the artifact of corrosion-causing chlorides.  

 

If you look closely, you may see colored clouds of chlorides and other corrosion products moving away from the artifacts towards the anodes, contributing to the active corrosion you see on the pieces of rebar. 

 

When the process is complete, these metal artifacts will be stabilized for long-term curation with an anticorrosive protective coating that will prevent any additional oxidation or corrosion.