Bluish White Film Inside of Old Whiskey Barrel

[Patrick McCauley]

Hi All. I'm on my third season with two 10 gallon #3 char former whiskey barrels. When I went to clean them in preparation for putting cider into them this fall, both barrels had a blueish white film inside of them. When scalded and vigorously shaken, it comes off like a skin. Both barrels were stored with a 50ppm sulfite and citric acid solution, which I "recharged" with additional sulfite and citric acid several times during spring/summer/fall, as the solution evaporated out, in order to keep them topped up. There's no smell, except the smell of a clean whiskey barrel. They smell great! I rinsed the barrels until no more bluish film would come out, and I plan to rinse them in Starsan just to be safe. Does anybody know what causes this, and if there is anything I should be concerned about? Would fumigating them with sulfur be a good idea?

Pat McCauley

Ann Arbor, MI, USA