Introduction: Electrolytic Rust Removal Aka Magic
This is a relatively simple, safe and cheap way to remove light or heavy rust from any ferrous object. I used this process to restore an old wood plane that I bought for $1 (it looked totally un-usable because of the rust). As opposed to grinding, heavy wire brushing and acid bath processes, this method removes none of the original steel and is not noisy or caustic.
How this works:
Several other sites do a better job of explaining the chemistry of this - but basically you set up a conductive solution and insert some sacrificial anodes. You hang your rusted tool in the solution and attach it to the negative end of the power supply. You attach the positive end to the anode and turn on the power. The current travels through the solution and in the process flakes off the rust - the flaking/softening occurs because of the reaction at the surface of the good steel that pushes the rust off.
See this site
for more info on the chemistry of it all. (now linked to a waybackmachine archive of the site - modern suggestions for this background are welcome).
Step 1: Gather Supplies
You will need:
This project cost me about $40 because I did not have access to a small battery charger. If you have a charger, then most folks with a decent shop full of crap can do it for almost nothing.
- Clean 5 gallon spackle bucket or other plastic container to meet your size needs
- 5 sections of 18” long 1/2” steel rebar ($5 at Home Depot –
buy in longer sections as needed) (DO NOT USE STAINLESS STEEL)
- 5 feet 12 awg (or so) insulated copper wire in two colors
- 5 yellow wire nuts
- several red wire nuts
- 5 feet pliable tie wire (non insulated) SEE UPDATE on Step 2 - the tie wire rusts out after about a year - you may want to use something more substantial or resistant to rusting.
- Box of washing soda NOT baking soda
- Anti-oxidant goo (IE Noalox – This is not necessary
but helps I think.
- Small battery charger or home made power supply ($20-$50 at AutoZone etc) - Its best if the charger
has a 6v option and an internal "trouble" switch that stops charging if something shorts out.
- Variety pack of alligator clips from RadioShack (unless charger comes with decent ones…)
- Outside outlet or extension cord
- GFCI protected outlet (this is a must in my opinion - working around power and water is stupid unless
you have GFCI protection
- 5 gal water
- misc clamps/small boards
- drill with 1/4 bit
- wire cutting and twisting pliars (linemans tools are best
- wire brush (better if on a grinder or dremel tool)
- anti rust spray or light oil
Step 2: Assemble Tank and Anodes
NOTE: Do not use stainless steel for the electrodes. As pointed out by a commenter on the intro page (thanks!) "The chrome in the stainless will leach out during the electrolysis and form hexavalent chromium compounds in your electrolyte. These are extremely bad for you." This is true - dont even think about using stainless steel for this project.
Assemble tank and electrodes
1) Space the rebar evenly around the bucket along the sides (running top to bottom). Mark the locations
2) Drill two small holes about 1/2 inch apart 2 down from rim for each rebar
3) Insert a 5" loop of tie wire through the holes around the rebar and out again . Lube the ends of the bar with anti oxidant compound and twist the wire tight and snip off so 1" of the wire is remaining. UPDATE: the tie wire eventually rusts out - mine in less than a year. Consider using something more resistant to rust - suggestions welcome. On the other hand, any time you are using electrodes, they are sacrificial - as is the wiring system that contacts the water, etc.
4) Once all rebar is in place, make 4 sections of copper wire with the ends skinned off to connect each rebar wire.
5) Wire nut each rebar to the next with a section of cooper wire (connecting the protruding tire wire (I also used Noalox on these connections). Do not connect the first and last rebar (ie: X---X---X---X---X---)
6) Add 5 tablespoons of washing soda to the bucket and fill within 2 of the rim with clean water (adding extra soda will not help&)
Step 3: Set Up Hanging Clips
1) Find a board (or any non-conductive object) to lay across the top of the bucket.
2) Attach a short lead of copper wire with an alligator clip attached to the water end. (I just stapled the wire to the board)
3) The clip should hang low enough to just enter the water. ( first photo below shows three clips - i was doing three parts at once..)
Step 4: Attach Charger
Don’t mess this step up – the polarity is important:
Make sure battery charger is OFF:
1) attach the positive (red +) end of the battery charger to the rebar wire
2) attach the negative (black -) end of the battery charger to the alligator clip over the water
3) I remember this by saying to myself “the rust flows off the tool towards the positive side”
Step 5: Attach Rusted Tool
1) clean a small piece of the tool where you will attach the clip - choose a place where it will also hang securely.
2) Attach alligator clip (which is attached to the negative end of the charger) and and hang the tool completely in the water. Its ok if the clip is in the water – it wont hurt it. Wiggle the clip to make sure you have a good connection.
3) Make sure the tool is attached firmly and is not touching the rebar or any part of the setup that is attached to the positive lead.
4) Areas of the tool that do not have a “line of sight” to the rebar will not be cleaned – if you have a complex part you might need to rotate it or add more rebar electrodes.
Step 6: Power It Up
1) set the battery charger to a low setting (6v – 1.5 amp works great for me)
2) Turn on the charger.
You should see tiny bubbles start to form all over the tool. As the process progresses, the rust will start to flake off and the water will become muddied with rust and goop and foam depending on how fast the bubbles are forming.
Step 7: Check Tool and Remove and Clean
Depending on the size of the tool, the amount of power used, the amount of rust, and your patience, the process will take from 1 hour to two days. The longer you leave it in the solution, the less work you will have to do to finish the clean up.
The tool will turn black and the rust changes form and flakes off.
If you leave it in long enough, you should be able to wipe the rust off with your finders and find a smooth (but pitted) surface. The nice part about this is that even after only 1/2 hour, the rust is much easier to remove with a wire brush.
NOTE: the tool will not come out of the tank ready to paint. it will still need wire brushing or final polishing with steel wool. the process leaves a gray/black layer of oxidant that you will probably want to remove prior to final rust-proofing or painting.
The photo of the saw below shows three stages: The left side was run for an hour and then brushed. The middle spot was steel brushed for the same amount of time but without the electrolysis (and rust remained) and the right side is the original rust.
Step 8: Samples
Here are a few samples:
The chisel was very rusted – normal rust removal would have required much original steel grinding to remove the deep pits that a wire brush would not have touched. Check out the stamp that was revealed after cleaning.
The entire project was started because I bought this sweet plane that was totally rusted. I only paid a few bucks, but knew that a used non-rusted one was worth quite a chunk of change. After the tank proces it took about an hour of going over it with the light wire brush wheel on the dremel to shine it up – but it would have been impossible without the electrolysis first.
Step 9: Final Rust Proofing
Step 10: FAQ
How big/small of an object can I do?
- My browsing around on the web found people doing anything from small parts in a 1/2 gallon tub to a trailer body in a swimming pool using a large welder for the power.
Does the solution "wear out"?
- No - it just gets nasty
How much power should I use?
- As little as possible to still get the job done. I think you will get better results with low power and two days of processing than high power and getting it done in an hour. The larger the object (surface area) the more power required to do it in a given amount of time. My charger is 1.5 amp 6 volt and works great for hand tools. the small stuff takes a few hours. The larger complex plane took a day and a half before i was happy with the amount of removal.
Is this dangerous?
- Only if you don’t have any common sense and don’t use a GFCI protected power source.
- Yes if you do it inside - the bubbles forming are evidently hydrogen which is flammable. Outside it does not cause any problems.
- The low voltage is pretty safe - especially if your charger has an automatic cut off "trouble" switch.
Are there any drawbacks to this system?
- Some people say that depending on the power and time involved, the steel can become brittle due to a temporary change in structure. This is cured by "baking" the tool for a few hours at 350 in the oven or letting it sit around for a few months before any hard use. see the links below for more info. I have not found this to be a problem.
These guys deserve the credit for teaching me how to do this and provide way more info on this system:
Participated in the
The Instructables Book Contest