I am thinking I want to make my own apple cider vinegar,,and I go to lots of auctions,at these auctions I see lots of old redwing crocks,I saw a 30 gallon today in really good shape,no cracks but it was pitting and a little flaky in the bottom,,so the question is are these safe to use this way?..it only went for around $85 so thats not bad,but I didnt want to buy it not knowing.