You could also try electrolysis.. http://antique-engines.com/electrol.asp
What you need:
* A non-conducting container - a large plastic bucket works really well.
* Battery charger - big is better, however even one able to produce 6 to 10 amps should do. A student recently used my site as the basis for a school project and used a computer power supply in place of battery charger.
* Sacrificial electrodes. Concrete reinforcing rod works well (rebar) cut into lengths about 4" taller than your bucket or container. Do not use stainless steel! The results are a health hazard and illegal (more on that later)
* Arm and Hammer LAUNDRY soda, also called washing soda.
* Wire and/or cables for connecting electrodes together.
* Small lengths of small chain (used to suspend the rusty parts in solution) or some other means to suspend the part to clean into the solution.
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