Oak casks have been used to age and transport spirits for hundreds of years. So what’s so special about oak?
Oak casks have been used to age and transport spirits for hundreds of years. The first spirit to be aged and transported in oak would have been brandy, probably in France or Spain during the 11th or 12th century. We don’t know for sure, but it’s a fair guess for two reasons: One, brandy was the first spirit produced in Europe, and it almost certainly happened in France or Spain where people were already making wine. Two, oak casks were the standard way of storing and transporting most goods for the majority of the last thousand years of human history.
So what’s so special about oak? Why not ash, or elm, or pine? Oak is an amazing gift from nature, perfect for building casks. It’s fast-growing, so it can be harvested and re-grown quickly. It’s naturally strong and flexible, so it can be bent into curved barrel staves, and can withstand impacts without breaking. It’s got a tight grain, so it will hold liquid without leaking. It’s got anti-fungal and anti-microbial properties which mean it can store food and drink for long periods without spoiling. Finally, the natural sugars and other flavours locked up in the wood add all sorts of complexities to wine, beer and spirits. And while there are experiments underway both in Australia and abroad to age whisky in other kinds of wood, 99.99% of all spirits are still aged in oak to this day.
Ageing spirits for the purposes of flavouring them almost certainly started as an accident. Because oak casks were already being used for storage and transportation, they would have been used for spirits in the same way they were used for nails, wine, salted meat, gunpowder, and pretty much anything else that needed to be stored or moved from one place to another. Once a spirit had been sitting around in the barrel for a while, medieval distillers and traders would’ve noticed the improved flavour, and decided to age spirits like brandy, whisky and rum deliberately. It’s important to note though, that until the 18th century, the vast majority of spirits, whisky included, would have been drank unaged and uncut, with only the wealthiest people drinking aged spirits.
These days, most single malt whiskies around the world are aged in ex-bourbon barrels due to the cheap and plentiful supply coming from the American whisky industry. We use a fair amount of them in Australia too, but one of the great things that sets us apart as a whisky producing country is our access to excellent wine casks. We have a thriving wine industry that allows us access to barrels of different styles and higher quality than many other whisky producing nations.
At Sullivans Cove, we use both American Oak ex-bourbon barrels and French oak ex-tawny barrels, but we’ve also been known to age whisky in Apera, Madeira, Chardonnay and other types of wine barrel, so you never know what we might release next.
Even in Scotland, where they’ve long used sherry casks to mature some whiskies, the casks they employed were generally the ones used to transport the sherry from Spain, not the ones used for the long sherry maturation process. These days, many sherry casks used in the Scottish industry are “conditioned” with sherry – filled for a short period of time to get some flavour. But here in Australia when we use Apera (Australian sherry-style wine) and tawny (Australian port-style wine) casks, they’re the real deal – often used to age those beautiful fortified wines for decades.