Be very careful running an electrical current through salt water, that generates chlorine gas. Very toxic stuff. In the quantities of salt water used to etch something it is not a problem but in larger quantities can be very dangerous.

Now if I get a piece of very rusty and pitted iron that I want to forge: will the rust burn in the fire? Or do I need to have a really clean surface prior to heat?

Ludo

Heat to red and wirebrush and the rust will fall off---note red hot rust chunks are uncomfortable on bare skin.

Any pitting may translate into a cold shut though so forge carefully.

What about the iron electrode?
The iron electrode works best if it :osurrounds the object to be cleaned:o, since the cleaning is "line of sight" to a certain extent. The iron electrode will be eaten away with time. Stainless steel has the advantage (some alloys, but not all) that it is not eaten away.
i don't quite understand this surround the object with the electrode???
what would the electrode look like?
explain by example, say a small jewelers vise.
buzz

Electrolysis uses positive and negative electrodes to create current. That current is unidirectional from one to the other. I use a battery charger and attach the negative clamp to the object, and the positive to a sacrificial piece of iron. If the sacrificial piece of metal cleans rather than the object, reverse the clamps. If you don't used a piece of metal, your clamp will become the sacrificial metal and disintegrate. If I need to surround a piece of metal, I would rig up a stand or something to hold the item upright in the water and then make a loop of wire or pipe to place around the piece attached to the postive clamp. That way all sides of the piece wich is essentially a negative electrode has a line of sight to the Positive electrode, aka:the sacraficial metal. Jeez, I'm confusing myself....so much easier to show than explain. If all else fails, just flip the object you want to clean and wait a little longer.

As a safety note, this will give off hydrogen gas DO NOT USE NEAR OPEN FLAMES. The amount is fairly minimal for most tool cleanings but better safe than sorry.

Buzz lets take your example of a jewelers vise: so the non greasy vise is put in a plastic bucket (needs to be non conducting) with the proper polarity wire attached to it.

The other electrode needs to "surround it" so for a small vise I might use a chunk of steel pipe that will surround the vise but not touch it.

The idea is to not short out the battery charger.

Using stainless as an electrode produces some really nasty haz-mat quality by products. All the advice I have seen is not to use it.

You only need electrodes 180 degrees or 120 degrees apart for coverage. Surrounding the part with electrode is better as there is more electrode and a shorter distance.

Is it possible to use an old mobile phone charger as a power source for this?
Keithwelds

IIRC time is a basis of current density so for very small items and very long times it might work.

I just picked up a 24 volt charger for an electric wheelchair that I plan to use for my new derusting setup.