Rust Removal via Electrolysis – An Overview

On the way home from work last night I was reading the woodworking sub-reddit and I noticed several posts about rust removal.  It seems like very few people are aware of how cheap and easy it is to use electrolysis to remove rust from tools.

Over the past few years I have used a pretty simple setup to strip the rust / paint off of my tools and I have been VERY happy with the results.  That said, I am in no way shape or form an expert on the subject so I do not know if this is appropriate for any collectable tools, but it works great for my users and involves little if any harsh chemicals or fumes.  I have never used EvapoRust but I used Navel Jelly and other similar products when I worked on the restoration team at the USS Missouri Museum and this process is safer and cheaper.  Plus there are no air-born particulates.

Electrolysis uses direct current (DC) power to transfer material from one piece of metal to another via a solution.  In our case, we are transferring Iron atoms from a sacrificial piece of metal to the tool in order to convert some of the “Red Rust” (ferric oxide) to “Black Rust” (magnetite).   The piece of metal to be cleaned is connected to the positive (red) terminal and the sacrificial piece is connected to the negative (black) terminal.  As the electricity travels through the solution, iron atoms are transferred from the sacrificial steel to the tool (along with some oxygen from the water) changing the Fe2O3 into Fe3O4.   In the process, the red rust that is not converted into black rust will come off and drop into solution.  Black rust is non-destructive (it does not flake) and it does not hold moisture like red rust so it actually helps to protect the metal from further rusting.  I’m not a chemist so take this all with a grain of salt.

The supplies you need:

-plastic container (I use a bucket or boot tray depending on what I am cleaning)

-12 volt DC power supply (I use an old laptop power supply)

-Baking Soda or Washing Soda

-Scrap Iron or steel (no stainless or galvanized)

-Wire

-Alligator clips (optional)

-Scrotchbrite sanding pads for cleanup (I use the “between finish coats” grit)

Power Supply

Most of the setups I have read about online used car batteries or battery chargers but I use a laptop power supply that I was able to get one from my IT department for free since it was being sent to recycling.  While they are lower power than the typical battery charger they are smaller, sealed (i.e. water resistant), and in my case free.  The lower power simply means the parts need to stay in solution for a longer time and I have a feeling there is less chance of damaging the parts being cleaned.

The modifications are simple, cut off the plug that goes into the laptop and identify which of the wires is positive and which is negative (the internal wires may already be color codes otherwise use a multi-meter).  I then connected longer color coded wires (in my case I used heavy gauge speaker wire from radio shack) and attached an alligator clips to make it easier to connect the parts being cleaned.

The Cleaner

May of the posts I read recommended using “washing soda” mixed with the water however I find baking soda is much easier to come by and since “washing soda” is simply a stronger version of baking soda you  can simply use more of the baking soda.  Typically I use around a tablespoon of baking soda per gallon of water, but I am not precise in my measurements.

Sacrificial Metal

For the process to work, the negative terminal needs to be connected to a piece of sacrificial steel or iron.  I have read that if stainless steel (or other steels containing chromium) is used the process can release toxic gases and will contaminate the water with heavy metals.  Additionally, you should avoid galvanized steel as you may end up Zinc plating your tool.  I typically use re-bar because it is cheap and easy to find but I think cast iron works faster (maybe the porous structure increases surface area?).  What is most important is the piece of metal should have a lot of surface area as this will dramatically speed up the cleaning process.

This piece(s) of metal will eventually become unusable due to the buildup of corrosion however in my experience you can use them for multiple cleanings.

The Process

Note: we are dealing with electricity and water together so be careful.  Connect everything with the power supply unplugged and if possible, use a GFI outlet.

Getting things started is simple: connect the part to be cleaned to the red wire; the sacrificial metal to the black wire and submerge both in the solution of water and baking soda, making sure the two pieces are not touching.  Now set you bucket outside and plug it in (this process can release small amounts hydrogen gas which is flammable in enclosed spaces so do this in a well ventilated area), you should see a bubbles forming on the surface for the part being cleaned or streams of bubbles reaching the surface within a few seconds.  Now sit back and wait.

How long?  That is the 64 thousand dollar question.  It is going to depend on the strength of your power supply, the level of corrosion, the strength of your cleaning solution, the surface area of your parts, etc.  I will typically check on the progress every few hours but seriously rusty parts I often leave overnight.

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Note the use of a nickle plated bolt, DON’T DO THIS.

 

When the parts are done, they will be black in color and you should see none of the telltale texture of rust.  Once it comes out of the solution you can either leave the black magnetite in place or remove it with a fine grit sanding pad.  You then want to dry the part quickly and apply oil as flash rust can appear quickly.

 

Sources:

http://myweb.tiscali.co.uk/andyspatch/rust.htm

http://www.woodcentral.com/cgi-bin/readarticle.pl?dir=handtools&file=articles_363.shtml

 

 

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Woodworking in The Berenstain Bears

I’ve been workshop free in Philadelphia at my in-laws’ house so no work has been happening.  Instead I decided to post some images from the Berenstain Bears’ New Baby in which papa bear does some green woodworking to make small bear a new bed.

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I’ve been reading this book to my son for months and this scene still bothers me, in particular the weird plane in Papa Bear’s tool box.

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Things are a bit more reasonable during the actual construction; note the stump and log work holding and another weird plane.

All for now, hopefully the new year will start with an assembled table top.

A different kind of woodworking – earthquake safety 

Several years ago I built a Lingerie Chest for my wife to make use of an empty space in our old bedroom.  In our new house it has ended up crammed next to the bed and the 4.0 earthquake last weekend (not to mention the toddler who has started climbing) forced me to finally put some earthquake straps on it.  

Since the piece is so narrow I get to attach both straps to the same stud but hopefully there won’t be and side-to-side movement.

  
I did not build the bedside table (which is actually part of a desk) which is a high quality Chinese Rosewood piece made in Hong Kong decades ago.  It’s on the bucket list.

Case Glue-up Difficulties

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You will notice that even though I have more clamps I still need more.

Just once I would like a large glue-up to go off without a hitch.

Last night I glued the top and back panel into place and it was a mess.  After a dry fitting that went together fine I took everything apart, made some clamping blocks, and laid out the readjusted clamps on my bench.  Then I brushed liquid hide glue on each piece and assembled the back and slid it into place (by badly cut dovetails in this corner as what allowed me to assemble it in this manner).  I start hammering and clamping joints closed and realize that top piece of the back panel wont seat with the side (right by the red WoodPecker angle piece).  Fist I try a mallet, no luck, then I try to clamp it which resulted in damage to the tongue (and cursing, thank goodness my son was asleep).

I finally give-up and take the whole assembly apart (score one for the long open time of liquid hide glue) and trip down the Douglas fir panel with a hand plane and the joint goes together with no problem.

Okay, add a bit more glue and put it all back together; wont go together again in the same spot.  At this point, I am livid and decide this joint is going together even if it breaks something.  I find a scrap piece with a groove in it that matched the tongue and release ever clamp except the one right over the joint and I crank it down, HARD.  It finally goes together, thank goodness, and I tighten every clamp down.  The back corner is a bit out of alignment but the front edge is square so I can live with that.

Musings on the current state of consumer furniture

I have been traveling for work this week so I have been unable to make any progress on my projects. Last weekend I assembled a piece of cheap furniture from Target; you know the kind, plastic wood grain over particle board (the irony being this shelf now holds my woodworking books and magazines).

As I was taking the parts out of the box I though the surface had been damaged, there were off colored parallel lines running along many of the parts. A close look showed no surface damage, that’s when I realized they were simulated milling marks. They had purposely made the surface of this furniture look like it has machine marks left on the surface.

This is what American consumer furniture has come to: Cheap fake furniture purposely made to look like badly finished wood furniture.