The Magic of Refill Casks

The vast majority of Australian whisky is aged in first-fill casks, resulting in big, bold and oaky flavour. But what about refill casks? How could this style of maturation, used commonly in the Scottish whisky industry, change the character of Aussie whisky?

Australia’s homegrown whisky industry is still very young, and as such most Aussie whiskies are also bottled young. Our warmer climate compared to places like Scotland, Ireland and Japan is also a factor in this, as warmer ageing conditions means more evaporation and oak influence in a shorter period of time.

As such, standard practice in the Aussie whisky industry is to age whisky in first-fill casks – ones that have come directly from the bourbon or wine industry and are still packed with lots of rich, oaky flavour. Sullivans Cove is no different, as our standard releases are generally aged in first-fill ex-bourbon or first-fill ex-tawny casks (although for quite a bit longer than most Aussie whiskies).

But in Scotland and Japan, it’s not uncommon to age whiskies in casks that have already been been used at least once to age single malt. These are known as refill casks. So what’s the difference when these kinds of casks are used?

Because refill casks have already been used at least once to age single malt, much of the oakiness and flavour from their original fill (bourbon, sherry, etc.) has been used up, meaning their influence on the final whisky tends to be much more subtle. Think of a teabag that’s already been used to make one or two cups of tea – you can use the same teabag again to make more cups of tea, but the flavour will be a lot milder. In this way, using refill casks allows the character of the spirit itself, often called “distillery character” to really shine through without being dominated by cask influence. Whiskies aged in refill casks tend to be paler in colour and more spirit-forward in flavour, with less of the big, bold, oaky flavours you would see from a first-fill cask.

Refill casks also tend to work well for long term ageing, because you can leave whisky in them for years and years without it becoming too oaky. Think of the teabag again; the second or third cup of tea will take a lot longer to brew than the first one. And as we’ve mentioned in previous articles (https://sullivanscove.com/journal/magic-of-barrel-ageing/), ageing isn’t just about packing as much oak flavour into a whisky as quickly as you can. All sorts of other magical processes happen inside a whisky cask over a long period of time that help to develop a level of complexity and texture rarely seen in younger whiskies.

For people who have been drinking whisky for a long time, the subtlety and nuance you can get from a refill cask is something to appreciate and cherish. Many fantastic independent single cask bottlings come from refill casks, and when you see the really old stuff coming out of Scotland that’s been aged for 20 years or more, many of the best and most interesting (at least in our opinion) have been aged in refill casks, too.

But don’t take our word for it. Legendary whisky writer Dave Broom recently visited Australia, and told us why he loves refill cask whiskies.

“For me, the three key elements for any whisky (or beer, or wine) are balance, complexity, and character. Cask influence plays a major factor in the first two. Too much wood will knock the overall balance. It will also reduce overall complexity. New oak casks are useful in adding flavour and giving a whisky a kick along the maturation pathway but can quickly dominate.

Character is the flavour signature of the distillery. It is what separates and defines each distillery. That is what always has to be paramount. Too much wood will obscure that. The whisky might be interesting, but it could come from anywhere.

It’s why refill casks are so useful. They give a more gentle maturation, reduce wood’s influence, allow more interaction to take place (adding to complexity) and preserve character. They are essential for longer-term maturation.”

If you want to read more of Dave’s brilliant insights into the world of whisky, be sure to visit his new website www.thewhiskymanual.uk

At Sullivans Cove, we’re lucky to have been making single malt whisky in Tasmania for over 25 years. That means we’ve got a couple of generations of 10-year-plus whiskies under our belt, including the casks that they were aged in, so we’re finally seeing some of our own refill casks coming of age.

In the coming days, we’ll release our first ever bottling of American Oak Refill Single Cask Tasmanian Whisky under our Cask Variations series. This whisky has been aged for thirteen years in American oak casks that were previously used to age an older batch of Sullivans Cove whisky. As far as we know, this will be a first for the Australian whisky industry.

Unlike the refill casks generally used in Scotland and Japan, these casks did not start their life in the bourbon or wine industries, but were originally commissioned by Sullivans Cove direct from the cooper as virgin (never filled before), medium-toasted American oak. After the original whisky from these casks was decanted and bottled, they were fully charred for the first time before being refilled with new-make spirit once again, then left to mature for thirteen years. The history of these casks is unique to say the least, and as far as we know, no whisky on the market has ever been aged in refill virgin, toasted American oak charred after the first use!

Julian White, co-owner of Whisky & Alement, one of Australia’s premier whisky bars, and one of our most knowledgable whisky minds, was one of the first to try this bottling, and had this to say about it:

“As ‘uniquely Australian whisky’ goes, the style guide generally sounds something to the tune of; made from Australian ingredients, distilled in pot stills to be a rich, oily spirit and aged in small format, fortified wine casks that have been re-coopered and heavily charred. While this doesn’t cover all Australian whisky, it’s certainly the ambition of many producers. And while Aussie whisky drinkers who enjoy an assault on the palate from fortified or table wine flavours might find this release from Sullivans Cove somewhat disinteresting, it represents an exciting new chapter for Australian whisky.

I was very, very happy with the balance of flavours that this whisky put forward. There’s complexity without punishment to the palate and freshness without youth. The Sullivans Cove team are to be commended for looking outside their comfort zone in selecting this cask for a special release. Many Aussie whisky producers would contest that this level of ageing in large format cask is unachievable, but perhaps this whisky proves that short term loses can become long term gains?”

Julian’s full tasting notes for this release can also be found below.

Unfortunately due to the ongoing COVID-19 crisis, Whisky & Alement has been forced to close its doors, but you can can now order whisky, including pre-packed tasting flights, from their online shop at whiskyandale.com.au/shop

Please remember to support small business in this time of crisis!

Nose:
Initially there’s preserved lemon and cassia bark, some fresh pencil shavings but not like those in a grubby old pencil case. As time goes on, the nose turns into marmalade and mango Weis bars. There’s hints of rose Turkish delight and roasted hazelnuts along with a very mellow roasted grain character.

Palate:
Tonnes of vanilla and toasted coconut (if you haven’t toasted coconut in the oven, do try it). The buttery characteristic that is uniquely Sullivans is easily picked up as the dram beautifully reflects the notes from the nose. Marmalade and tart fruits. The way the timber displays itself on the palate is really what sets this dram apart. Only the lactones and delicate spice characters are expressed rather than the aggressive aspects of new or even first fill timber. So instead of highly jammy notes of apera or tawny we get creamy vanilla, Frosty Flakes and delicate Earl grey tea.

Finish:
While the abv. sits at a friendly 47.5% keeping the grippy length at bay, it’s the sugars that really hang about on the palate. The marmalade notes of caramelised orange also linger and exhibit all the good work done in the brewing and distilling phase. The age of this whisky is certainly its defining factor, allowing the subtle arrangement of fruits, sugar and timber to come together and wipe off those youthful notes. It sets this bottling apart from many other Aussie whiskies on the market today, who’s youth unfortunately overshadows the brewing qualities which are at the heart of all good whisky.