De-rusting old parts with electrolysis
Posted: Thu Jul 18, 2013 10:04 am
I was introduced to this process a couple of years ago, and use it all the time.
You'll need:
* An old plastic bucket or container big enough to fit the part you're cleaning
* Water
* Washing soda, aka electric soda or sodium carbonate. Look in the laundry isle at your local woolies
* a 12(ish) volt DC power source like an old battery charger or power supply
* tie wire and hookup wire
* a few pieces of scrap metal (mild steel, not stainless)
Here's a pair of manky old brackets I found, I'll de-rust one of them:
Fill your bucket up with enough water to cover the part, then hang the part in the bucket with a piece of tie wire.
Place a piece of scrap steel on the opposite side of the bucket, making sure it can't touch the part.
To clean both sides of the part at once, use one piece of scrap steel at each end and suspend the part in between the two.
Connect the part to your power supply negative, and the scrap piece(s) to positive.
Your scrap steel needs to be clean, and have a surface area bigger than the part you're cleaning, so thin sheet is better than solid bar scrap.
It will also be eaten up by the process, so don't use anything you'll miss!
Then add a small amount of washing soda. A tablespoon or two is all you need.
If you add too much the process can be too agressive, plus it's just a waste.
After a minute or two you will see some small bubbles forming on your rusty part:
The next day it will look a little bit different:
For large and/or really rusty parts they might need to be in the bath for up to a week.
Each day or so you'll need to change the water and replace (or at least clean off) the scrap steel.
To clean up an old bench vice I found in a wood pile, it took about 4 days in the bath.
And here's the original bracket, the de-rusted one (after wiping down with a rag), and the sacrificial scrap steel:
The brackets are hot rolled steel bar, so that's about as good as it ever looked 
The parts will start rusting again pretty quickly so either paint the part, or give it a quick spray of wd40.
Washing soda is pretty tame, and although the bath looks pretty horrid at the end it's about the least toxic liquid you'll have in your shed.
And the reason why you don't want to use stainless steel scrap is that there's a risk of hexavalent chromium exposure, so stick with mild steel!
You'll need:
* An old plastic bucket or container big enough to fit the part you're cleaning
* Water
* Washing soda, aka electric soda or sodium carbonate. Look in the laundry isle at your local woolies
* a 12(ish) volt DC power source like an old battery charger or power supply
* tie wire and hookup wire
* a few pieces of scrap metal (mild steel, not stainless)
Here's a pair of manky old brackets I found, I'll de-rust one of them:
- brackets1.jpg (36.36 KiB) Viewed 4712 times
Place a piece of scrap steel on the opposite side of the bucket, making sure it can't touch the part.
To clean both sides of the part at once, use one piece of scrap steel at each end and suspend the part in between the two.
Connect the part to your power supply negative, and the scrap piece(s) to positive.
Your scrap steel needs to be clean, and have a surface area bigger than the part you're cleaning, so thin sheet is better than solid bar scrap.
It will also be eaten up by the process, so don't use anything you'll miss!
- bath.jpg (114.6 KiB) Viewed 4712 times
If you add too much the process can be too agressive, plus it's just a waste.
- washing_soda.jpg (33.15 KiB) Viewed 4712 times
- bubbles.jpg (41.27 KiB) Viewed 4712 times
- rustybath.jpg (57.52 KiB) Viewed 4712 times
Each day or so you'll need to change the water and replace (or at least clean off) the scrap steel.
To clean up an old bench vice I found in a wood pile, it took about 4 days in the bath.
And here's the original bracket, the de-rusted one (after wiping down with a rag), and the sacrificial scrap steel:
- bracket_after.jpg (48.74 KiB) Viewed 4712 times
The parts will start rusting again pretty quickly so either paint the part, or give it a quick spray of wd40.
Washing soda is pretty tame, and although the bath looks pretty horrid at the end it's about the least toxic liquid you'll have in your shed.
And the reason why you don't want to use stainless steel scrap is that there's a risk of hexavalent chromium exposure, so stick with mild steel!
