A mate uses 60L garbage bins, ~$10 from Bunnings at the mo. Little bit of bleach or napisan, leave them in there for about a week, comes up apples and the labels slip off. Good thing is, he reckons the bins hold just the right amount of bottles for one batch. I just soak mine in tubs on the lawn and I've got a scrubbing brush with a sharp plastic edge and wire and soft bristles, works well on any stubborn glue I come across, but after ~1wk of soaking, not much stays behind....except those #%@@%*& crown labels...I'm over those.