The Arm and Hammer washing soda is to enhance the conductivity of the water
(electrolyte) and is not a cleaning agent.
The Cathode (part to be cleaned) is hung from a steel wire or chain attached to
the Negative (-) lead of a battery charger and then immersed in the electrolyte.
The Anode (sacrificial scrap metal) is attached to the positive charger lead (+) with
a steel wire and immersed in the electrolyte, or the positive lead can be clipped to
the scrap metal if it sticks up out of the container or is above the electrolyte.
The anode and cathode or any of the leads much not touch each other at any point.
The battery charger must not have a built in polarity protector unless that feature
can be turned off, or you will need to use a battery as the power supply and the
charger can then be connected to the battery. In this case both the battery and the
electrolyte will be giving off small amounts of explosive gas, so use necessary
precaution with sparks or flames and provide some venting. Turn off power when
connecting or disconnecting power supply leads.
Here is a breakdown on my small parts “Rust Bucket”