Combine pickling salt and sugar, mixing thoroughly.
Clean cabbage and cut heads into quarters. Shred enough cabbage to fill 10 litre bowl, then place shredded cabbage into the bottom of the crock. Sprinkle 1/3 cup of salt/sugar over cabbage, mix thoroughly in crock and knead cabbage with your hands, until it becomes juicy.
Repeat layers until crock is full. (A layer is one 10 litre bowl of shredded cabbage plus 1/3 cup salt)
Place plate on top of the last layer of shredded cabbage. Carefully place rock onto the plate and cover with a large tea towel. The kraut needs some air so a single layer cloth is all you need. For proper fermentation, let the crock stand at room temperature for one week.
Pack sauerkraut into jars. Boil the jars in a canner for 20 minutes. Remove the jars from the canner & tighten the lids then place them upside down on a towel to seal. Store in a cool, dark place.