# What current and voltage are best for electrolysis rust removal?

I weld carbon steels all the time, and sometimes I get parts from the scrapyard. Unfortunately, these parts are generally oxidized, so I've been assembling an electrolysis tank for it. This tank removes the oxidation in about a day. I'm getting the feeling that I can make it go faster if I step up the current or voltage. What combinations of currents or voltages would make the fastest method of removal?

NOTE: I'm familiar with the risks of doing electrolysis, including hydroxy production, and the restriction on stainless steel electrodes.

• What is the applied voltage? Did you try just HCl? – Jaroslav Kotowski Sep 17 '15 at 10:42
• I use 12V at 2A. I'm using NaOH for the electrolyte. Approximately 1 tablespoon per gallon with 15 gallons. – Sarah Szabo Sep 18 '15 at 3:36
• and what about the HCl? – Jaroslav Kotowski Sep 18 '15 at 10:12

## 2 Answers

This is what I found (only in Czech):webpage

Power source should be around 15V/5A. The cleaned part acts as negative electrode- applied voltage should be as high as needed to reach 2A. The electrolyte (described in the source) is based on water and sodium carbonate. Derusting should be done between 2 to 4 hours. Let us know if it helps or how it works.

In order to answer the question we also need how large a part you are electrolyzing.

The current density in $mA/cm^2$ is the key number. For electrolysis on stainless steel, I would say you need to stay less than about $1~mA/cm^2$ to stay safe.

The voltage is hard to gauge. In any two electrode system like yours, the electrochemical potential is only one part of the total potential. The total potential includes contributions from the resistance of the solution, resistance of the contacts, overpotential of the counter reaction, etc... The current should be a decent gauge of what you are seeing.