I used the Tim Allen approach (more power!) but learned that over about 40-50 amps the bubbling is so vigorous that the liquid isn't in as much contact with the part you're trying to clean and it is less efficient. I'd set the welder at 25-30 amps, go mow a section of the lawn and come back to re-adjust the electrodes or part or what have you and always had great results. Took off oil, grease, paint, rust, anything - and didn't eat away the part like a sand blaster would. Either more soda or have the electrodes closer - they both amount to the same thing which is less resistance between the part and the electrodes through the liquid. A small green bean can worked well for bolts and nuts i wanted to save, and 8-10 pieces of rebar around the sides of a 5 gallon bucket worked well for larger parts. I used a concrete mixing tub with 20 pieces of rebar for flywheels or water tanks for old hit and miss engines too... suppose an old wash tub would work well too but would be harder to clean the rust out of when it got dirty.
One great benefit is cleaning of cast iron cookware. blasting with sand would load the pores of the cast iron and prevent cooking properly. i cleaned an 1860's waffle iron that had been painted and hung on a wall and it came out shiny light grey, perfectly clean pores, seasoned it and still use it.
