Cast iron cleaning doesn’t have to be hard – and using a lye bath is no exception.
Please take all necessary precautions when using lye – it’s a dangerous chemical, can cause burns that you do not want. Use good long sleeved rubber gloves and at minimum a pair of safety glasses. Some people prefer a face shield.
Lye is Sodium Hydroxide, it’s able to clean most old seasoning and sludges from old cast iron pieces, and it won’t hurt the cast iron itself. I’ve left pieces in the lye bath for weeks and no harm came to it. You will need a pure lye, not drano or other drain cleaners as they are chemical concoctions that you don’t want on your cast iron piece. The only places in Alberta that I know carry it are home hardwares, but check around – Home Hardware lye.
One of the main advantages to lye is that it’s effortless, put your pieces in, make sure they are fully submerged and take them out periodically for a manual scrubbing. Some pieces will be clean in 6 to 12 hours, others may take days. Let the lye do it’s job. You may find that lye alone cannot handle the entire cleaning, and that’s where electrolysis comes in handy. There is a writeup Electrolysis cleaning.
You will need a container that can handle your cast pieces. I use 2 large rubbermaid totes, one inside the other for added strength to handle multiple pieces. Some people use 5 gallon buckets, choose whatever you want.
WARNING! – Always add lye slowly to cool water and stir it – NEVER add water to lye or the resulting chemical reaction can cause harm to you and your surroundings.
Fill your vessel with as much water as you need then add your lye – the recipe is 1 pound (454 grams) to 5 gallons of water. If you have 10 gallons of water, use 2 pounds. I like a stronger solution, so 1 pound of lye per 4 gallons of water. Mix it well and add your pieces.
That’s all there is to it. Be patient and good luck.