What you'll need:
• Plastic or glass container big enough for your part. I use disposable lunch meat containers with lids.
• Water
• Wire. NOT copper wire.
• Sodium Carbonate; not to be confused with Sodium Bicarbonate (baking soda). This is commonly sold as Ph Up for pools/spas. I get the Clorox brand at Walmart. You'll have enough to last you the rest of your life.
• Power supply. You can use a wall charger in just about any voltage. 12V is good but lower is fine, it just takes longer. Take your old power supply, cut the barrel end off, split the wires, and put alligator clips on each wire. One positive & one ground, of course. I use a desktop power supply but I do a lot of geeky stuff so it was worth the investment for me.
• A "sacrificial" piece of steel. I use a scrap of sheet metal from my body repair on the Datsun. You can use a clean bolt. Whatever. Remember, it's sacrificial, though. You'll see why.
What you'll do:
1) Fill the container with water and toss a small handful of Sodium Carbonate in there. I have no specific measurement. I'd say for my container, it's probably less than 1/4 cup of SC. Stir well. I use a bamboo skewer for this.
2) Tie your piece to be cleaned with wire. In this case, I'm de-rusting some nuts. *snicker* <--juvenile humor. Wrap the wire onto a stick, pencil, skewer, whatever and place the stick across the container with the part dangling in the "soup". Clip your NEGATIVE lead to the wire.
3) Put your sacrificial piece in the container and clip your POSITIVE lead to it. DO NOT let the sacrificial piece/+ lead touch your part/- lead.
4) Once that's all set up, plug 'er in.
You'll see all kinds of frothing and the rust hunks will start to float off your part and onto the sacrificial steel. It's pretty awesome.
This probably goes without saying but keep this sciency goodness away from kids and pets & make sure you have a window open, at least. It doesn't stink or anything but it does off gas & naturally, you don't want to go huffing it.
Let your soup cook for a few hours or until your part is no longer nasty looking. The part will come out black but when you rinse/brush it off with water, it looks like metal again.
Tips:
Scrape all the big, nasty scaly stuff off your part and generally clean it before doing this process.
The solution will look awful but all the gack settles to the bottom & you can reuse it. Store with a lid on and MARK it! The sacrificial steel is pretty much shot, but I rinse it off, and next time I stick the clean end in the solution. Once the whole thing is all icky, it's done. You can technically still use it but the current doesn't flow well so don't bother.
Here are some pics.
The setup
A good example of what happens when you use "dead" sacrificial steel (almost no action).
VS good sacrificial steel. Lots of frothy goodness!
Before:
After. This photo shows a penny I nickel plated, too. That's also a cool process I use on some of my parts.
This is why the piece of steel is sacrificial. All that gack came from your part:
Have fun!
