Electrolysis Rust Removal

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Sharkey
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Electrolysis Rust Removal

Post by Sharkey »

OK, new project: 10 meter amateur radio antenna.

Materials: Old CB base antenna the previous owners left behind.

New technique: Remove heavy rust from antenna mounting bracket without sanding, scraping, grinding, etc.

Here's how:

This antenna had been left out in the weather probably since it was new, first up on the roof where the antenna was initially used, then sitting around as junk in the yard for who knows how many decades. I tossed the antenna in a pile of "useful" metals that I didn't recycle when I cleaned up the yard after moving in. Last week, I decided to see if I could salvage the antenna and use it with my HF ham rig to give me a backup communications link into town in the event that the 2 meter repeater croaks.

The steel bracket for the antenna was badly rusted, so much so that it had deep pits where the rust had eroded the base metal. Normally, this would require a lot of effort to clean up, then it would need to be treated with phosphoric acid, then worked on some more before maybe being ready for primer. It would likely rust quickly, even with a topcoat of paint.

Then I remembered something that I read on a VW diesel forum some years back, a method of removing rust from steel parts using electrolysis. I decided to try it out. I hacked a hole in the side of a gallon drinking water bottle, half-filled it with spring water, sprayed some Easy-Off oven cleaner on the surface (because that's all I had that was a strong base, sodium hydroxide), and lit it up with a battery charger. After a few hours, it looked like it might be working somewhat, so I moved it out to the photovoltaic array and ran 24 volts into the electrodes. This produced more current, and intensified the results. Here's a photo of the process with an anode (+) of mild steel hanging from two bailing wires suspended by a stick of hardwood. The antenna bracket piece is on the left, connected to the negative (-) battery terminal. A little more than two amperes is flowing:

Image

Removing the bracket from the bath and hosing it off with clear water shows how much of the rust has been removed:

Image

The line near the top where the bracket changes color shows the difference between the untreated top of the bracket where it stood above the solution and therefore wasn't cleaned by the electric current.

The next day, I went into town, and while there, picked up some Arm & Hammer "Super Washing Soda", which is called for instead of the lye mixture I was using. I neutralized the lye with vinegar, and dumped it out. Refilling the bottle with clean water and a tablespoon full of washing soda gave even better results, more current flowed and the cleaning process accelerated.

Here's a piccy of the bracket after another hour or two in the bath, and after I shot it with the sand blaster just to pretty it up a bit:

Image

The coupon of steel on the left is the metal I was using as an anode (positive pole). It is a clip of corner bead from the sheetrock work I've been doing in the house. Any old piece of steel or cast iron will work. I went through three pieces of this material to clean both bracket pieces. A larger, thicker piece of steel might have lasted a lot longer, but this was a trivial thing to replace during the process.

All I can say is "This WORKS!!!" At no time did I have to scrub the bracket with anything more than a worn-out kitchen scrubber to brush off the loose carbon that used to be hardened rust. I could even have done without the sand blasting, but since I have the gun, I decided to use it. The bracket (and it's mate) is now coated with cold galvanizing paint, with no rust underneath to spread.

You'll notice that I haven't given specific instructions for doing the electrolysis. That's because there is a PDF of the procedure over at the stovebolt.com site, and I'm just going to send you to that instead of trying to repeat it here:

http://www.stovebolt.com/techtips/rust/electrolysis.pdf

If you have rust to remove, this is worth looking into. You can do jobs of any size and it doesn't take any more equipment than a plastic container and a car battery charger. Check it out, try it and see!!!
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Post by Bob »

That is something really worth learning! Great for smaller things that can fit in the container, but is there a way to do that on something like part of a car body? BTW...thank you for sharing all this "smart" stuff with us all, I feel I should offer the teacher an apple! :)
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Post by Dennis The Bus Dweller »

How about that, Thats great
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Post by stuartcnz »

At work, we run a current onto all of the wharf piles (steel surrounded concrete) to stop them from rusting, in their sea water environment.

Preventitive electrolysis.
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Post by Sharkey »

Bob, I think that the size of the work piece is only limited by the capacity of the container that you are going to immerse it in. The PDF does describe using towels saturated in the soda/water solution and applying them to rusted areas that can't be dipped.

I tried to find a more technical description of what this process does, but didn't have any luck. The closest I came was treating rusted steel with phosphoric acid, which does the same thing chemically, but takes longer because it's less active:

http://en.wikipedia.org/wiki/Rust_removal#Rust_removal

I've used phosphoric acid to flash mildly rusted steel previous to painting, but never tried to do it without a lot of hard sanding with an angle grinder and sanding disk. Even that and hard wire brushing does not get into the pores, which is what the acid is for. I'm much happier with the results and lack of effort this method returned.
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Post by ezrablu »

Cool post Sharkey! I ran across this last summer when I was trying to find out out to clean up some old iron skillets I bought at a thrift store.

http://www.youtube.com/watch?v=fm0d3qojmDg&NR=1

http://www.youtube.com/watch?v=uRhNvD4eIFk
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Post by Stealth Camper »

Bigger parts.

I guess the first thing I would try would be to build up a frame with concrete blocks, plywood/2x4's or something substantial like that. Then line with thick pvc plastic sheet or EPDM sheet (like a pond liner). Fill with solution.

Wow! When I read that back it just sounds really dangerous! Maybe find someone nearby that strips big parts. Or a sandblaster for cars (walnut shells?).
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Post by Sharkey »

What? No one in your neighborhood has a swimming pool?
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Post by TMAX »

stuartcnz wrote:At work, we run a current onto all of the wharf piles (steel surrounded concrete) to stop them from rusting, in their sea water environment.

Preventitive electrolysis.
We used to have a similar setup in AT&T for some of our underground diesel fuel tanks. Here in the US it is called cathodic protection.
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Post by TMAX »

Sharkey wrote:What? No one in your neighborhood has a swimming pool?
Our pool is salt water now... we're halfway there.
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Post by stuartcnz »

TMAX wrote:We used to have a similar setup in AT&T for some of our underground diesel fuel tanks. Here in the US it is called cathodic protection.
That's probably what it's called here too.
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Post by Stealth Camper »

Next neighborhood over has the swimming pools. I live in the "cheap seats". But I haven't seen any of them apply electricity to the water. Yeah, I know...24volts won't hurt much. Still, I would be afraid of discoloring the tile!

But then a concrete pool might provide enough alkaline?? Wonder how long a gunite pool would last as an electrolysis tank?
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Post by rlaggren »

Forgot where I read this (don't _think_ it was here...). It has worked for me a couple times.

Regular white vinegar will de-rust metal; but it will do it over a period of days. So will other mild acids, and if you're timing is good, probably strong acids. Rust dissolves quicker than the base metal. But the vinegar works and is safe and easy if you've got the time. Put a lid on it so the solution doesn't evaporate.

Mild acids are also used to sharpen files. Just clean out the file and dump it in the vinegar for a few days.

Speaking of removing coatings, house paint, either oil or latex, will come off metals if left in a bucket of plane water for a week. Raising the temperature may speed the process some. This has been handy for me when dealing with old window hardware. I pull the window, remove the hardware and dump it in a bucket; by the time I've stripped the paint off the window, replaced rotted wood, glass, etc and repainted, the hardware comes clean with a stiff nylon parts brush.

The older ye get the lazier ye get. <g>

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Post by ezrablu »

Kind of like "set it and forget it" :D

I think to think of myself as more "mellow" than lazy. And not really "older" just wiser :roll:
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Post by rlaggren »

Well now, that's a truly enlightened way of putting it.

I've noticed the last few years I seem to have developed a habit of letting a lot of problems set a while, see if it has enough staying power to be there in the morning; give it a chance to elope with some errant solution that comes along... Like maybe one of my nephews or nieces. <g>

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