23 June, 2014

Letting the cauldron boil and bubble the rust away

What a busy last few weeks it has been, toiling away in the old stone Garage.  In a very short time, the Maxwell looks like a car again, and I'm starting to realize that this folly of an adventure may actually lead to a working car.  There are many unknowns, but it's wonderful to see.

I'll update you more completely in a future post, but I want to touch on a topic I've mentioned in passing several times this summer without a proper explanation:  Electrolytic rust removal.  Yes, I can hear the droves of people (probably all four of you) heading to the exits at this point, but stick with me!  I promise this can be a helpful topic.  If nothing else, hang around to see how many times I've shocked myself by trying to mix electricity with water...

Here's the test item hanging from the board before cleaning.
My delving into electrolytic rust removal actually started a while back, after reading about the topic on countless restoration websites.  They say it's a hands-off way of removing all of the rust from the surface of metal without the messy grinding, naval jelly, WD40 or other wives' tales of how to get something clean.

Let me preface this by saying that the process works, and it works really well.  But how?

I don't want to bore you with a sciency explanation of what regular, red rust is and why it's bad, because believe me, I could (and I would probably be the only one enjoying it).  In order for you to understand electrolysis, though, you have to know some things in a metal nutshell.

The point is, after getting weathered over time, a chemical reaction takes place at the surface of a metal object, and the process of the metal being eaten away leads to rust forming from the new compound---iron oxide.  This happens when metal is exposed to water and carbon dioxide.  The iron acts as an anode, which means it gives up negatively charged electrons, while other parts of it act as a cathode, which is the opposite.  This is what usually can be brushed off or flakes off when the part is handled.  Underneath is basically newly-formed magnetite, or "Black rust," which is what we're working to reverse (I swear this knowledge will come in handy later).

Here's my initial setup with rods and wires. It's not high tech.
In most cases, when water hits the metal, whether through rain or humidity in the air, the water and carbon dioxide that makes up a portion of our atmosphere (0.04%) combine to make an acid.  The oxygen component of the acid reacts with iron and oxidizes it (which means that the iron loses electrons.  The opposite to this is called reduction, which is gaining of electrons).  The electrons go from anode to cathode, or from negative to positive.  Think of it like how one end of a magnet is only attracted to the opposite end of another magnet.  Like charges repel, opposite charges attract.

So, once we know this, how can we reverse the process?  The metal underneath the outside corrosion should still be okay (unless it's really rusted all the way through), so we need to remove the rust without hurting the underlying metal.

So let's use electricity and water---two things that you normally shouldn't combine, but since this is The Garage, why not?

Alright, ready to connect!
To set up your electrolysis, you'll need a five gallon bucket, five gallons of water, some washing soda (this is different than baking soda), some metal wires, a battery charger and some pieces of metal that you don't mind getting really rusty.

After filling the bucket with five gallons of water, add five tablespoons of washing soda and mix it in.  Washing soda is not baking soda.  The former is sodium carbonate and the latter is sodium BIcarbonate.  Long story short, the former makes the process go faster than the latter, but if you can't find washing soda, baking soda will work, just not as quickly.

Using the wire, connect all the pieces of sacrificial metal together in a series, but do NOT close the loop, as your battery charger won't appreciate it (one of many ways that you can upset your charger).  Set these pieces of metal (rebar works extremely well and is quite cheap) into the water, but make sure one of them sticks up above the water so you can connect the battery charger.

The next step is to submerge the item you want to de-rust in the solution.  It is extremely important that you don't let the object touch any of the metal rods, or else your battery charger will get very angry (thankfully this is easy to avoid depending on how you wire your rods together, which I swear is not a euphemism).

The way that I first did this was to set a piece of wood across the bucket (since wood does not conduct electricity), then hang my part from it using a separate piece of wire.  You can also submerge your metal part into the water if part of it stays above the water line.  Then you can clip the battery charger here instead of the wire.

Either way, when you're ready to start, hook the positive lead from the charger to one of the rods (or to the wire connecting them).  You need to make sure all of your connections are tightly wound to the rods and the object, or else this won't work.

The negative lead will attach to the object/the wire suspending the object.  You can check the connections in the rods by lightly brushing the negative lead against each one to see if there's a spark.  If not, readjust the wires and make sure they are wound tightly around the rods.  It may also help to run the portion of the rod where the wire wraps around it under a wire brush to make sure you have the cleanest contact possible.

When your connection is solid and the charger shows a current is flowing, you should notice tiny bubbles coming from the metal part and around the rods.  Congrats!  It's working!  But why?

By adding sodium carbonate to the water, you're giving the newly-made solution a way to carry ions between your anode and cathode, creating a current.  Sodium is positive, so it will move to the negative connection (the part), whereas the carbonate is negative, so it moves to the positive.  This helps create an environment where the black rust can be reconverted into iron.

So once the part is cooking, you can leave it for several hours, and it should be fine.  Just as a heads-up, use only regular iron pieces in the solution.  Trying to de-rust any plated metal or stainless steel or anything won't work very well, and it will release dangerous gases (which are never good).  Also, don't spend a ton of time breathing in the gases from the regular process, either, and avoid sparks or open flames while you're doing it, too.  The process won't suddenly explode, but why take a chance?

The pick head after it was taken out of the solution.
After the piece has been in the solution for a while, you should see its surface turn black in places, meaning that the process is actually working.  When you remove the part, IMMEDIATELY wipe the piece dry, removing that black coating and staving off the corrosion from starting right away.  You can even run the part under the wire brush after drying it off, and this should yield a brilliant, bare metal finish.  But know that this bare metal is again susceptible to rust, so either prime and paint the piece or oil it right away.

So has this worked for me?  Absolutely!  I tried cleaning a random pick head that I found in The Garage a while back.  It didn't have a handle, and it was rusty, so it seemed perfect for an experiment.  I hung it from a wire and dipped it in the solution, letting the cauldron boil and bubble the rust away.

Oh, hello Beale Brothers logo.
When the day was done, I removed the piece and wiped it dry, suddenly noting the wonderful manufacturer's logo on its side.  I had never been able to see it before!  From this information (and in true Garage fashion), I found that the pick was 100 years old and produced in Alton, Illinois, by the Beale Brothers Company, which ceased existence well before 1920.  Go figure!

I have also cooked several Maxwell parts in the solution, from the coil holder to the brake rods and exhaust manifold.  With each of these, I let the piece stay in the solution for several hours before wiping it off, running it quickly under the wire brush and priming it (except for the manifold, there).  I'm always amazed at what brilliantly shiny metal awaits under the black coating, and I know with certainty that rust will not suddenly spring up from under my primer and paint, since I eliminated nearly all of it in the process.

So yes, electricity and water together are normally dangerous, but as long as you pay attention and make sure your setup is sound beforehand, you will soon have the most thorough solution to rust problems, and it won't even require grinding, lathering on naval jelly or being covered in dust after wire-brushing the rust away.  This novella of a public service announcement was brought to you by Woodsie's Garage.

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