**NOTE: While my shop is pretty much electron free woodworking, this post is all about using electrons directly. Ironic, no?**
I was telling a friend and co-worker about my experiences using electrolysis to remove rust from tools and thought it might be time for a post on this subject.
But before I get started let's just clarify a few things:
1. I am NOT claiming to be an expert on this, but I have had quite a bit of success with this method. Most of this I learned on the Internet - but as far as I know, the "CAT Scan" set-up is my own idea.
2. Be careful - this does involve electricity and water and it gives off hydrogen and oxygen gas. I recommend doing this outside. (Which in Alaska, makes it a summertime only activity, so obviously these pictures are not current - actually, judging from the shop in the background, they are even older than I remembered!)
Okay, let's get started. For this example we will be using a Stanley #65 low angle block plane. Here's the before and after shot:
I probably should have taken pictures of a more dramatic de-rusting. This tool was not too bad to start, and I could have simply went at it with some steel wool or sandpaper. But, the difference is that with electrolysis, you don't hurt the tool at all. No abrasion, no lost of metal (pitting will still be there however). It is a little like magic when you wipe it off after its bath.
Sacrificial iron or steel
Car battery charger with ammeter
Assortment of alligator clips/leads
Washing Soda (Baking Soda works too, just not as well)
Here's how it works in a very general way. The tool and the sacrificial metal are attached to the UNPLUGGED battery charger (Important! tool = negative, sacrificial metal = positive) and placed in a tub of water that has an electrolyte (washing soda) added. When the charger is plugged in and turned on, the electric current flows between the tool and the sacrificial metal and a lot of cool scientific stuff happens! Basically, some rust on the tool is physically blasted off by the bubbles of gas coming off the surface and the rest of the rust on the tool is converted back into another form of iron. While this is happening, the sacrificial metal is, well, sacrificed in a slow and painful (okay, not really...) way as it somehow erodes into the water. Also at the same time, oxygen and hydrogen bubbles are, well, bubbling up.
Now you know why I don't teach science! If you are interested in the exact science of it all there are a ton of sites on this that explain it much better than I do - just google "electrolysis rust removal" and start reading. But seriously, whether you understand it or not, it still works!
On a more pragmatic note, here are some things to keep in mind:
1. Keep an eye on the ammeter - not enough current and the process will take forever - too much current (red zone on meter) and you might fry something.
To increase current either add more washing soda or move the tool and metal closer together (Unplug First!)
To decrease current either add more water or move the tool and metal farther apart (Unplug First!)
2. If the bubbles slow down, but the tool is still rusty, take it out (Unplug First!), wipe it off, and restart.
3. The process is "line of sight", which means you will either have to be patient and rotate things around, or be impatient (like me) and get creative...
4. If the water turns green and foamy, RUN! Just kidding, it's normal.
5. When you take the tool out it will start to rust again. Fast. No really, FAST! Be ready to dry and oil/wax it.
To help deal with my impatience I created a "CAT Scan" rig that placed the tool inside a tunnel of the sacrificial metal.
Here's the carrier board that holds the tool parts. It has holes drilled into it to allow zip ties to be used to secure the parts (you do not want them coming into direct contact with the other metal). These holes also allow the current to get to the bottom of the parts.
Now the carrier board and attached parts is placed into The Fully Adjustable Tunnel of Rusty Doom!TM The vertical "tail" on the tunnel allows the battery charger jaws to be clear of the water (so as not to participate in the sacrifice below the surface).
Each part is wired up to a short jumper bar which will be connected to the battery charger (again, out of the water).
And here is a shot of the rig up and running on the back deck.
A last couple of before and after shots.