Saturday, February 20, 2016

Rust By Any Other Name

So now on to the results of my electrolytic rust removal 'science fair' experiment.  You'll notice that I used some extra solid copper wire to ground the hub rotating assembly to the spindle.  This was to ensure a good electrical connection between the two, ensuring the treatment would act on both.  Don't worry about any potential side effects on the longevity of the bearing, as I planned to replace them all along anyways.  This just allows me to use what I've already got for measurements and mock-ups.

Picking up where the experiment left off last last time, is the spindle immediately after the electrolysis treatment had completed:

Quite a difference!  Now that pretty black coating electroplated on it is actually not desirable, and needs to be removed.  Also note that some areas, like the rotor/wheel register don't have it.  That's because this process only acts on the rusted surfaces, and any rust that was in those areas was little more than superficial surface rust.  I chose to let the spindle soak in a mild acid solution (Distilled Vinegar) for an hour or so to soften the black coating, This was followed by a good thorough scrubbing with a small wire brush, revealing the bare metal underneath:

Now we're getting somewhere!  This is actually after a quick dip in water to neutralize any remaining acidity on the surface.  Also note that I was able to get the wheel speed sensor off, which thankfully when the bolt is no longer rusted in place, a conventional 6 point 1/4" socket will fit firmly enough over the external Torx head fastener to remove it.  However, at this point, my freshly bared and unprotected metal was rusting right before my eyes as the part dried.  I had heard it would rust within the hour, but we're talking by the second.  So I decided to speed up the process by using a hair dryer to get the water out of all the nooks and crannies.  It was both intriguing and concerning to watch the rate of 'flash rusting' multiply with the forced air drying.  This is where the Scotch Brite pads came in handy:

Holy crap nuggets!  I never thought the spindle would ever look this good again.  The flash rust was totally eliminated, leaving the surface of the part at least stable enough to take a few minutes and spray a coat or two of high temp primer on it:

So there you have it...A cheap, but admittedly more involved than anticipated, method for taking ugly rusted parts and making them look nearly as good as new without any fancy equipment.

Now, apparently pure carbon/graphite rods for the anodes will not produce the floating rust-sludge, eliminate the need to regularly clean the anodes, and doesn't require as much cleaning of the finished part either.  In other words, the whole process would be significantly cleaner and easier.  If I was de-rusting parts on a regular basis, or doing so with a large quantity of parts, this would absolutely make sense.  However, it's considerably more expensive, and much less readily available locally, than mild steel.  If I can find a few rods for cheap enough, I would certainly consider this for the other spindle, but I won't be holding my breath for that to happen.

Wednesday, February 17, 2016

Evil, Thy Name Is Rust

Well, nearly a year has passed with no physical progress on the car.  Plenty of investigating new ideas, designing, and planning have occurred, but nothing tangible.  However, I got the perfect Valentine’s Day gift from SWEETA this year.  Garage time!  Not just after everybody had already gone to sleep, like I normally relegate myself to, but during the day as needed to take on scourge of steel…Rust. 

The previous weekend, I had actually started modifying the spindles to accept a standard aftermarket lower ball joint.  This needed to happen before I could take measurements that would allow me to design a front suspension geometry that will match my preliminary rear geometry.  The problem being that I also was uncertain that these particular spindles would be worth continuing my efforts with, as they were originally purchased back when we lived in the rust belt, and looked every bit of it. 

I looked into potential alternative spindle options, but decided to first see just how well these ones might clean up.  A little research into de-rusting methods led me to decide on electrolysis.  I mean, if it works on unwanted hair…So why not unwanted rust, right?

So here the setup for my little ‘science fair experiment’ that I ran over the weekend. 

There is an array of three pieces of scrap mild steel* that act as the anode, being sacrificed to the car gods.  Well, I hope they were scrap.  But it’s been a long time, so I’m not totally positive.  Then again, if they weren’t scrap before, they certainly are now. 

The part being de-rusted acts as the cathode, and the battery charger supplies the necessary electrical current.  The bucket is then filled with an electrolyte solution** typically made from 1 tbsp washing soda or baking soda per gallon of water.  Apparently you can also convert baking soda into washing soda by baking it…Which begs the question of whether that means you can also convert washing soda into baking soda by washing it?  Anyways, after adding 4 gallons of the electrolyte mixture to the 5 gallon bucket, I was ready to go.  Almost immediately after plugging in the battery charger, set at 12V/10A, it started to work. There was a ‘fizzing’ of hydrogen*** and oxygen being released, and while rust particles began to invade the solution.

After a while, the water began to look much less inviting.

And whenever the amperage would drop into the 2A-4A range, I knew the anodes could use a cleaning.

At this point, I would skim the surface of the water to remove the sludge buildup on the surface…After unplugging the battery charger of course.  I would then remove the part from the water (rubber gloves are helpful here), transfer almost all of the solution to a second bucket, dump the little bit of heavier sludge**** that had settled on the bottom, clean the anodes, put it all back together, and top off the water.  Remember that while the release of hydrogen and oxygen may lower the water level, the no sodium carbonate is released from the solution.  So the only need to add sodium carbonate that needs to be added is to account for any solution lost during de-sludging.

As time passed, obviously the amount of rust particulate in the solution increased.  However, I also noticed a corresponding increase in the frequency of needing to clean the anodes, and the aggressiveness with which I had to do so to get good amperage when I resumed the process.  Early anode cleaning was sufficient with a wire brush, but as the electrolyte became more contaminated I would then hit it with a flap disc on an angle grinder too.  Of particular interest was that the spindle didn't appear to be changing anymore, about 12 hours in or so, but I was still getting the floating red sludge.  So I decided to totally change out the electrolyte solution, and hit the anodes with an abrasive disc again.  Voila! There was nothing but pure electrolysis for the next few hours, with virtually no new rust particulate in the water, rust formation on the anodes, or loss of amperage.  My experiment was complete.

So, how did the parts actually turn out?  You’ll just have to wait until the next installment to find out…And I promise it won’t take another year!

*If you would rather not get or give cancer, don’t use stainless steel as your anode.  While this requires less cleaning than mild steel, it releases toxic hexavalent chromium into the solution.

**If you would rather not wage chemical warfare on yourself, much like my previous entry on Phosgene, don’t use table salt (sodium chloride) for your electrolyte.  While this will create an electrically conductive solution, it releases toxic chlorine gas.  Which can additionally combine with the released hydrogen to create hydrochloric acid.

***If you would rather not have your workspace go the way of the Hindenburg, keep your setup in a well ventilated area and keep it away from sparks or flames.  This includes pilots for gas water heaters.  It is also one of the main reasons for unplugging the battery charger every time before moving anything around on the setup.

****If you’ve followed the preceding  precautions, the mixture ‘should’ be non-toxic and environmentally benign.