I send it out to a specialist shop.
They use a very large DC power supply- I believe its about 100 volts, 1000 amps, but I am not sure about that.
They buy their acid from a supplier- almost all the commercial electropolishers in the USA buy from supply houses. The acid is a secret recipe, the supplier does not tell exactly what is in it, but as I understand it, it is mostly phosphoric acid. However, they wont tell what other ingredients are in it, or what the dilution is.
The acid is placed in a very large heated tank- the guys I use have a tank that is bigger than 1 meter x 1 meter x 2 meters, heated somewhere around 100 degrees farenheit.
The rigging of the piece is an art- there are eddy currents from the electricity, and how the piece is racked, as well as where the electrode/anode is located in the tank affects where the polish is better or worse, and part shape affects this as well, so a good shop may have a variety of racks and know tricks on how to rack a part to get complete polishing in difficult areas.
Time in tank varies depending on original finish of parts- I do a lot of heavily forged stainless steel, which is black when I deliver it, and they sometimes have to leave it in the tank for 30 minutes or more, while machined parts with a factory mill finish may only be ten minutes- but that is with their enormous power supply.
Many home experimenters in the US use auto battery chargers, which, being so much less powerful, require much longer times in tank. Hours and hours, in some cases. Also, home experimenters seem to have been having success with citric acid solutions, which are much safer and more convenient to work with.
