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  • Making a Coopered Barrel

Making a Coopered Barrel

There are many traditional tools and techniques specific to the trade of Coopering. It was a pleasure to be shown some of these by Master Cooper Andrew Young, who along with inventing many innovative methods still uses traditional tools in his daily work.

Andrew has access to a seemingly endless supply of well-seasoned American and French Oak that has been recycled from Seppeltsfield’s collection of old casks. Andrew wastes nothing, he salvages every last thing, down to the tiniest oak off-cuts that fuel the fire pot. He only uses straight grain timber that contains about 14% moisture to make his casks. The casks made in Andrew’s cooperage are designed for fortified wine from Seppeltsfield or whisky from Lark Distilleries in Tasmania.

To prepare the recycled staves, he first cuts them to size and then spoke-shaves them clean and shapes them on a on a shaving horse. There is no glue at all in Andrew’s casks, years of experience ensures that he can create joins that will be watertight when the cask is full. The oak timber can vary in density so Andrew takes great care to make sure he alternates hard and soft staves around the girth of the cask.

A marvellous tool is used to cut the angle on the edges of the staves - a Cooper’s Jointer, I had never seen one of these before and I was very impressed, I think that all workshops would benefit from having one of these. They are essentially a giant hand plane inverted and supported at an angle on a cast iron stand. The cooper shaves the edge of the stave over the razor sharp blade by hand, achieving the desired angle more or less by eye. The angle is determined by the diameter of the hoop and the number of staves to be used in the keg. The staves are also tapered at the ends to give the barrel its characteristic oval shape when the ends are drawn together.

Once the staves are cut to length and the angles jointed, they are arranged inside a steel hoop. At this stage they protrude straight out towards the bottom in a fan shape. The cask is then put over a fire pot and heated to make the timber more pliable.

The cask is heated over the fire pot for an hour, it’s held just off ignition point. After an hour it’s taken off the heat and hosed down, the water creates steam that aids in promoting the elasticity of the timber. The staves are drawn together using different sized hoops, they are held in place with an iron truss ring. Once the cask is bent into shape it goes back on the fire again. This is done for 15-20 minutes each end in order to take the
stress out of the bilge (middle). As well as de-stressing the centre of the cask this added heat also opens the pores of the wood allowing for maximum flavour from the oak to be released into the wine from the open fibres. Finally the hoops are fitted whilst the cask is on the fire.

Wine reacts with the timber in differing ways to whisky. If a cask is destined to store whisky, it’s actually set on fire so as to leave a layer of carbon on the inside. The charcoal is a filter for the whisky. It takes a lot of knowledge and experience to know how far to go with the toasting. It’s a dramatic and slightly unnerving sight to see a new cask being set on fire.

To create a rich, deep plummy flavour in the whisky, Andrew likens the process to cooking a steak. He says it isn’t a matter of just putting a roaring fire underneath it. First you must bring it up to a certain temperature and hold it there to lock in the flavour, and then the temperature is raised until the cask ignites, producing charcoal.

The ends of a cask are known as the head, they are made up of boards pushed together using double-ended nails. No glue is used at all. The heads are marked out using a compass. The heads aren’t round as you may expect, but slightly oval in shape to allow for expansion across the grain of the head as there is compression in the cask once it’s full of wine. The edges of the head are double-bevelled. This bevel is referred to as a basel and is cut using a cooper’s drawknife or heading knife.

The basel fits into the croze, this is the groove that runs around the inside of the top and bottom of the cask. A cooper’s adze is used to cut the chime; this is the heavily angled edge that sits just above it. The size of the head is measured using a cooper’s compass by taking the measurement within the croze. This is cut using a croze plane or cooper’s router, which it like a rebate plane with a rounded base. This isn’t the easiest of jobs and takes a lot of strength.

The bottom head is fitted by loosening the hoops and pushing the heads down into the croze, the top head is then pushed into the top croze. In France they use flour and water in the croze when they fit the heads, Andrew laughs as he explains that the French hate it when we joke with them that they use glue to put their casks together. Here, Andrew uses linseed meal with all the oil extracted from it, water is then added to make a paste. The paste acts as a lubricating agent to allow the head to be moved more easily into the correct position.

If there are any joints that are not perfectly fitted, Andrew uses river reed or bull rush to close up any small gaps. He split the reed and slides it between the staves to create a watertight finish.

The hoops are fitted and tightened into place. Finally the bunghole is drilled and the cask is filled with fortified wine or whisky so it can work its magic and age gracefully.

If you find this subject interesting and would like to know more, we stock a book entitled The Cooper and His Trade by Kenneth Kilby. This book covers the history of coopering through to the present day.

You can arrange to see Andrew Young at work in his cooperage at Seppeltsfield. Click here to find out about the cooperage tour or any of the other wonderful tours at Seppeltsfield Winery.