Rust removal magic!

[Binford]

I have heard about this for years on Jeep forums. Not on the boating forums though, strangely enough. And until today though, I've never tried it.

Before I hauled the seized engine from Chopstick II (the new boat) to the scrap yard, I pulled off all the useful parts. One of them is the exhaust riser elbow. Pretty rusty though:



There might also be a crack at the outlet, which looks pretty badly corroded.


So the technique I am using is electrolysis. I put three pieces of rebar into an old 5-gallon plastic bucket, wire-brushed off the rust on the rebar at the top of the bucket so I would have good contact points to attach some copper wire to connect them all "electrically." They will serve as the anodes:




Next I filled the bucket with about 4 gallons of water and added 1/3 cup of washing soda. I then put a coat hanger through the exhaust riser and suspended the part in the middle of the solution, not touching the rebar anodes. The part then becomes the cathode:




Finally, I connected my battery charger's positive clip to the rebar anodes and the negative clip to the coat hanger suspending the part. When I turned on the battery charger (set at the low, 2-amp, charge level), current began flowing and little bubbles of hydrogen and oxygen gas immediately started flowing up and stirring the solution. A bit of rusty scum is starting to build up on the surface:




I'll leave it like that for a few hours, then pull the part out and examine it. More later.....

[Flingarrows]

When you say washing soda, is that like baking soda, or something else?

[randyscycle]

That process does work, but you'll need to change the water and clean off the rebar a few times during the process. It also will leave behind a black coating of iron phosphate on the part you are "cleaning"

[fng]

I did this same thing on a fuel tank. Got pretty good results.

[jeeper]

I tried it myself on some headers once. It worked okay but took a long time and as Randy said it leaves a black coat that doesn't easily come off.

I didn't need to change the water but I did need to clean the electrodes a few times.

[Binford]

When you say washing soda, is that like baking soda, or something else?

Washing soda is sodium carbonate as opposed to baking soda, which is sodium bicarbonate. It's sold in stores as "Washing Soda" such as this:



That box is about the same size as a cereal box, by the way. Cost about $3.50.


Does the iron oxide have to be removed, or can it be painted over?

[militarypotts]

That was like a science project for school.

[kwai]

You should be able to paint over the iron phosphate. Ospho converts the rust to iron phosphate and they say you can paint over it.

[Flingarrows]

Washing soda is sodium carbonate as opposed to baking soda, which is sodium bicarbonate. It's sold in stores as "Washing Soda" such as this:



That box is about the same size as a cereal box, by the way. Cost about $3.50.


Does the iron oxide have to be removed, or can it be painted over?

Thanks Tim

[Binford]

You should be able to paint over the iron phosphate. Ospho converts the rust to iron phosphate and they say you can paint over it.

I called it "iron oxide," which I guess the black stuff is a form of. Technically though I understand it's magnetite, or Fe3O4, which I guess is the black stuff on magnetic tape used for tape recorders. I have also heard it called iron phosphate.

Whatever the stuff is, I plan to thoroughly rinse the part when it's finished in the bucket of magic, scuff what I can off with a Scotchbrite pad, rinse with hot water and dry it quickly, then paint it.

I unplugged it last night (my better sense and my better half caused me to do that!) and just plugged it back in this morning. So we'll see how it looks this afternoon.