Wednesday, September 26, 2012

Iron Relic Electrolysis

In my last post, I showed off a couple of cool iron relics that I recovered at the site of Mower's Charge in Bentonville, NC.  Lead and brass relics can be damaged by farm equipment, construction, fertilizer, and moisture in the ground, but are typically fairly stable once removed.  Iron relics, on the other hand, present an interesting challenge.  While they are also damaged by time underground, the rate of corrosion of iron objects rapidly increases once brought out into the atmosphere.  As a result, we have to take steps to remove the oxidation (rust) that is present upon recovery and protect the artifact from further damage.

One of the most effective methods for removing the rust layer is known as electrolysis.  Here's a picture of my electrolysis rig, and although it's a bit crude in aesthetics, the design is essentially the same as those used by universities and professional laboratories to preserve iron artifacts.  NOTE:  Electrolysis can be a very dangerous process, involving electricity with exposed wires and the generation of potentially harmful, flammable, and/or explosive gasses.  Don't try this at home.  Or if you do, be safe, use adequate ventilation, and don't say I didn't warn you.

My rig consists of a plastic container (in my case, a 5 gallon bucket) filled with an electrolyte solution (I used Cascade dish soap, primarily sodium carbonate).  In the solution are two electrodes.  For a positive electrode, I used stainless steel flashing left over from a construction job (EDIT:  I've recently learned that SS results in harmful byproducts, and should be avoided.  Use iron rebar, instead).  As you can see in the picture, I used two pieces on opposite sides of the tub to provide an even current distribution, and connected them together using four lead wires.  The negative electrode will be the iron relic to be cleaned.  In my setup, it is suspended by a crossbar using two connected wire leads.  It is very important that the two electrodes not come into contact with each other!  The positive and negative electrodes are connected to a battery charger (I used either 12V 6A or 12V 2A settings, depending on the object being cleaned).  When the current is supplied by the battery charger, the relic will start to bubble as iron oxide is stripped away, leaving a rust-free artifact.  If you're interested in learning more, I would highly recommend this video from relic hunter Beau Ouimette showing his electrolysis unit in action.

Here is a before and after showing the CS pentagonal cavity shell fragment after the first round of electrolysis.  I will most likely run it through again to remove some of the remaining stubborn rust spots, but you can already see a tremendous improvement.

A more striking example is the lock plate from an Enfield rifle found last weekend.  What was once a glob of rusted iron has been transformed to reveal the mostly-intact mechanism from inside the rifle.  The next step will be to remove excess water from the iron by soaking in acetone, and finally sealing the relic with a hot wax to prevent further rusting.

I do hope this post has been helpful (or at least entertaining).  Thanks for reading, and I look forward to showing you what I dig up next!


  1. Be careful with using Stainless Steel. It makes the water very toxic with the same chemical that Erin Brochovich (sp?) fought PG&E for the town that had the cancer cluster in California. There really isn't a safe or healthy way to dispose of it. Try using a 2' piece of cheap rebar instead. Here is a link to one article with more information on using stainless steel

    1. Thanks! I've amended the main article to include this information!

  2. Also, If you use rebar and a washing soda, such as Arm & Hammer, you can dump the byproducts on your lawn and your lawn will be lush and green without any repercussions.