My wife collects cast iron cookware and I get the privilege of cleaning it. I built a electrolysis tank. I use a 12v battery charger and arm and hammer washing soda. Arm and hammer washing soda is a sodium carbonate as baking soda is a sodium BI-carbonate, You can put bi-carbonate into an oven and cook it at 200 degrees for an hour and convert it to a carbonate. The battery charger needs to be powerful enough to get the job done speedily. I use a SCHUMACHER SE-5212A-CA Smart Charger,50/10/2A. It runs at nearly 10 amp continuous which make for a faster cleaning cycle. Make sure the charger is a manual charger as the automatic chargers don't work for electrolysis. I clean several skillets at a time so I use a big tank. Electrolysis is the best way to clean cast iron.