Tuesday, January 13, 2015
by Anson Kritsch, University of Iowa Office of the State Archaeologist
Many artifacts from the Hubbard Park excavations are made of metal, and as we all know - metal rusts. Several of these artifacts could contain important time sensitive information beneath all that rust. Patent numbers or company names on rusty artifacts help determine the age of features. So what is to be done? Easy - just remove the rust using electrolysis. Though it has a complicated name, it is a very simple process.
Electrolysis involves running electricity through water to remove rust from an object. To understand electrolysis, you only need to understand two simple processes. First, electricity flows from negative to positive. Second, when electricity comes in contact with water, it separates water into its base elements of hydrogen and oxygen.
First, we suspend the artifacts in a vat of water. Then we connect the rusty artifact to a negative terminal. Next we connect a piece of metal to the positive terminal. Finally, we run a steady stream of electricity from the rusty artifact to the piece of metal through the water. As the electricity flows from the artifact the surrounding water begins to separate into its base elements, creating hydrogen and oxygen bubbles. These bubbles act like micro explosions that blast the rust off the artifact’s base metal. After several hours, voilà we have a rust-free artifact. Take a look below at the toy gun found at Hubbard Park.
We also use a de-corroder solution to clean some smaller metal artifacts. So far we have used this solution to remove some rust off shotgun shells and several coins. See some pictures below.
Toy gun before being run in the electrolysis machine.
Toy gun after being run in the electrolysis machine.
1879 Penny before soaked in de-corroder.
1879 penny after de-corroder soak.
1907 Hardware Convention Token after de-corroder soak.
Shotgun shells on the left before de-corroder soak. Shotgun shells on the right are after de-corroder soak.
Here is an inside look at the tank.