"Skin bottles for carrying various fluids were made by killing the chosen animal, cutting off its head and feet, skinning the carcass, and sewing up the skin, fur side out, to seal off all orifices but one (usually the neck). The skin was tanned with special care to minimize disagreeable taste. In time the skin became hard and brittle. If new wine, still fermenting, were put into such an old skin, the buildup of fermenting gases would split the brittle container and ruin both bottle and wine. New wine was placed only in new wineskins still pliable and elastic enough to accommodate the pressure. –227