In chemistry and manufacturing, electrolysis is a technique that uses a direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially highly important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell.
Restoring iron relics – What I’ve learned from my mentors. By David Bond
1st thing to consider is the fact that electrolysis will not only dissolve the rust, but will eat away at your cathode (Relic) as well. & Too much amperage can be bad. “The slower/ lower amps, the better” especially on badly deteriorated iron…… sometimes its best to skip straight to using #4 below… Depending on how bad the relic is.
1) Electrolysis: I always use carbon steel plates as my anodes. I do a lot of electrolysis in my shop, so I stay away from using stainless steel…. like from welding stainless, electrolysis will also release Hexavalent Chromium, which is a cancer causing toxin. If you do use Stainless plates as your anodes, do it outside.
I use baking soda or washing soda as my electrolyte solution…. two teaspoons per gallon of distilled water will do the trick. There are tons of videos available on how to setup your own electrolysis kit. Attached is a pic of an 18th century shingling hatchet im restoring, just for reference.
After electrolysis or mechanically (wire wheel, brush, or pic) removing rust, here are a few other steps to consider using to stabilize/restore your iron relic.
2) BOIL: Most relics are found in high grounds such as around old farms, where the soil is somewhat stable. But old iron relics that are found near rivers or highly mineralized areas…. Once you remove the iron object from the ground it will rapidly begin to deteriorate due to the high mineral/salt content. If that is the case, the best way to stabilize the iron is to boil it in clean water until the water is clear (After you have removed most of the rust). Note that iron is porous. This process will remove salts and minerals from the iron that are causing the deterioration. You may have to do this several times. This will stabilize the metal and keep it from deteriorating any faster.
3) Evaporust: comes in a one gallon jug, about $25. You can reuse the liquid. Place your object after electrolysis, or if just a little surface rust, into a tray and pour evaporust over it, let it soak. This will remove most of the remaining surface rust. Pour the used liquid into a milk jug to be reused again. Let it dry, then…..
4) Tanic acid powder: Mix a 30% solution.. 3 parts tanic acid powder and 7 parts distilled water. Per a buddy of mine, it needs to look like green tea. Soak the iron object in this solution. The iron will soak up the tanic acid. It will react with the rust and kill it. The iron will turn black. This method works better than just using a rust inhibitor coating, as the iron will soak up the tanic acid, thus extending its life.
5) Then, brush on 2 coats of Gempers rust inhibitor. Goes on purple, Black when cured. Let 1st coat dry to black before applying the 2nd coat. Allow 2nd coat to cure for 24 hours.
Final Result: You have a museum ready restored relic that will most likely never rust again if cared for properly.