Maintaining whisky casks
Whisky casks are vital to aging quality whisky. And, much like the whisky itself, they are organic, living things. The condition of a cask impacts the flavours, aromas, and character of the final whisky. And the condition can change over time, as the wood itself ages. So maintaining the casks, and ensuring their condition remains optimal, is important.
In this article, we'll look at five steps to maintaining whisky casks.
1: Warehouse environment
Keeping the warehouse at an appropriate level of humidity is key to preventing the cask from drying out. Dry casks can warp, crack and ultimately leak. And we don't want that. In a humid environment, the whisky inside the cask evaporates more slowly. This helps preserve the whisky’s volume while allowing the spirit to mellow gradually over time. It also helps keep the wood in good order, reducing the risk of leaks.
Temperature changes in the warehouse can cause the wood of the cask to expand and contract. This impacts how the whisky is absorbed into, and interacts with, the wood. Casks stored in cooler climates mature more slowly, while warmer climates lead to quicker maturation. In of itself, this is neither positive nor negative. The dynamic can be used by clever warehouse keepers as a mechanism for influence maturation. Want a cask to age quicker? Put it in a warmer part of the warehouse. Want slower, more gradual maturation, choose a cooler spot. Where one needs to be careful is extreme swings in the temperature which might put extra strain on the wood of the cask. This may lead to cracks and leaks. Perhaps less of an issue for Scotland, but important to monitor in warmer climates - like America.
Allowing fresh air to circulate the casks is important for ventilation. Many traditional, or "dunnage" warehouses have earthen floors. These earth floors help maintain a natural climate with good air circulation. In modern warehouses, proper design and equipment can help ensure appropriate air circulation.
2: Rotating and re-racking casks
It's easy to imagine whisky casks being left in a certain corner of a dark warehouse and left to sit there for decades. And, indeed, sometimes this is the case! But, in a surprising number of instances, reality is more involved. Casks are rotated around the warehouse to different locations to influence the way they mature. And whisky can even be changed from one cask to another to further develop flavour, known as re-racking.
3: Monitoring fill levels
Over time, a portion of the whisky will evaporate - famously known as the 'angel's share'. This is a natural part of ageing whisky, and no bad thing in of itself.
However, carefully monitoring fill levels is important. Excessive loss may be a sign of a leak. And even if there's no leak, losing too much volume can be undesirable for obvious reasons. And worse still, losing too much ABV and sinking below 40% would mean it cannot, at least as a single cask, be classified as whisky.
So, a warehouse keeper will regularly 're-guage' a cask to check its volume and strength. Where necessary, further action can then be taken.
4: Repairing casks
As the wood of the cask ages, it can develop issues. Staves can become loose or cracked, cask ends (heads) can crack or separate, and the hoops can become loose. A warehouse keeper's, or a cooper’s, skill is invaluable in identifying problems early. They can detect changes in the wood or structure and fix them before they deteriorate.
Minor leaks can often be fixed with a small piece of wood. In cases of larger cracks or splits, more significant repairs may be required by a cooper. And replacing or tightening the hoops ensures the cask remains strong.
5: Record keeping
Perhaps the less glamorous side of maintaining whisky casks is ensuring accurate record-keeping. Every cask is unique. Keeping accurate records helps track its history, characteristics, and maintenance. This paper trail is vital to the cask's history and is important evidence when casks are bought, sold or bottled. Making a record of where the cask came from, when it was filled, what type of wood it is, and what it was used for previously helps document how the whisky's flavour may develop. Repairs should be recorded, along with tasting notes that capture flavour development over time.
Sourcing, storing, and maintaining casks
If you need help sourcing, storing, or maintaining whisky casks, we can help. We have years of experience in sourcing the best whisky casks. And our dedicated warehouse Braeside Bond can help you store your casks, while carefully maintaining them as they age. You can enquire about buying whisky casks here, and contact Braeside Bond warehouse here.