Distilled Spring 1984. Sazerac 18 year old rye is an interesting spirit, a rare spirit, an epic spirit. It’s released just once a year as part of the equally epic Buffalo Trace Antique Collection, with just 28 barrels per bottling. Since at least 2006, the single source for this bottling has been a distillation completed way back in 1985 and put into stainless steel tanks sometime in (or after) 2003. So each year, the Sazerac 18 is the exact same whiskey, with the exact same time aging in oak barrels, but just a year older in the tanks. John Hansell over at Whisky Advocate reported on the details of this case a few years ago, pointing out that it was originally stored in a 13,500 gallon tank, then moved to three individual 2,100 gallon tanks to lessen the interaction with oxygen (though not treated with inert gas to completely stop oxidation).
Clearly, there is still interaction with oxygen – each year, the Sazerac 18 tastes a bit different, and each year, there is a bit more loss to evaporation, even in stainless steel. In 2007, the net loss from original barreling was 51.9%. In 2008, it jumped up to 54.1% (maybe that was when they moved tanks??). Then 56.1%, then 56.5%, then 57.3%, and now 57.6% with this 2012 release. Even still, the annual Sazerac 18 bottlings are kept at a constant 90 proof.