Rust electrolysis troubleshooting question...

[timbn2]

I'm using a 25 amp rectifier similar to the one sold by Caswell. I have 6 pieces of rebar around a 5 gal bucket all wired together with copper wire. i have the red lead on that an the black lead on the part... or more precisely to copper wire wrapped around the part. I used 1/2-1/3 cup arm and hammer WASHING soda in water as the electrolyte fluid.
i tried 2 different small parts (brake master cylinder) and a 1/2" rod ranging form 15 min to 2 hours on 8-12 volts. the most amps i ever got at the highest volt setting was 5. Does that sound right, or should i be getting more amperage at 12 volts?
also regardless of the time, there didn't seem to be a whole lot of rust removed on either part. the water defiantly had rest in it and so did the re-bar and the part was "bubbling" like its supposed to.
The master cyl. only had very small amount of rust on it and it still had some on it after about 1 hr?

Did i do anything wrong? Do i just need to leave my parts for more time? I am also told that as soon as the part is de-rusted the reaction will stop despite current flow. is this true?

thanks a lot!

[jrow]

timbn2,

I believe your amperage is to low. Try a battery charger! With the rectifier that you have it's going to take a while.

John

[timbn2]

why might my amperage be to low...i mean is there anything i can do to increase it? its a 25amp rectifier so how do i get full amperage out of it?
thanks

Tim

[CarWiz]

First off, the process will work with low draw. If you want to increase the draw, you can add more soda or a 1/4 - 1/2 cup of phosphoric acid ("metal prep" in most home centers or hardware stores--In the paint department). Also, don't use copper wire in the solution. Use steel wire or old coat hangers.

The process converts the iron oxide (rust red) into a ferrous compound (black) that must then be washed off. When using soda alone, the process will stop when the rust is converted and no metal will be lost. If you add the acid, you could loose metal over time but it does help the flash rust problem.

It will take at least over night to do most parts. I've left parts in the tank for three days for heavy rust. It is a slow process so don't rush it.

Here's a piece I did some time ago. Before:



After (With a little paint)

[chromo]

Wow Carwiz, that looks good.

What kind of machine part is that? I have a lathe that is getting rusty. Mostly 3 jaw chuck, crosslide bed, tool post, etc.. type parts rusting in high humidity. Any advice on cleaning and some how sealing then to stop the rusting. Just oiling them is not working well when not use for periods of time.

[CarWiz]

The piece is a radius and angle dresser tool for shaping grinding wheels. The shaped grinding wheel is then used for grinding tool bits or special shapes. It has a diamond bit at the end of the tool bar.


Humidity is a problem in this area too. The problem could be the oil you're using. You didn't say what you're using but WD-40 is worthless in this case. Use way oil on the slide surfaces. LPS#3 is a good long term coating for other parts. It's a little waxy but for long stretches between use, it's probably the best. Keep things coated even if you have to make it a weekly job. Reducing the humidity and/or controlling temperature swings are the best way. Not knowing your situation makes it hard to define a solution. A 60w light bulb tucked into a machine can help too.

[tbreaden]

Check your wiring the red + goes to the part being stripped and the black - to the re-bar. and run it to 12v if possible.

[CarWiz]

Nope. It's the other way around. Positive goes to the anode (steel bars), negative goes to the part being cleaned.

[tbreaden]

You guys are talking about electro-stripping. Where do you get your info? Look at Caswell Plating Manual pg. 30

[timbn2]

well, the "overnight" part worked. I guess i just needed to be a bit more patient. it is working and working well, just a lot slower than i thought. I did swith from copper wire to an old coat hanger (suspending the part in the solution) and that seemed to help with my amperage.
thanks all for the input.
Tim