My friend and I are new to canning, and having some trouble with the double boiling aspect. At first we used a rack, but the calcium build up from the water eventually started flaking off the pots and racks. We used vinegar to clean them, but it seemed eventually that started making everything rust. We can several batchs a day, so we end up losing a pot and rack within a couple weeks. We tried double boiling in a regular stainless pot without a rack, and now our pots are starting to discolor. From a different forum on this site, I see we need to use a rack, but can someone explain why we can't just skip that part and just put the jars in the pot? Or is that why our pots burn?
Also, is there any other way to clean the calcium and keep them from rusting?