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'Scotch Bonnets' created to reduce Angel's Share

A Dundee-based company has come up with a simple device designed to ensure that minimises the 'Angel's Share', lost through evaporation. The device is inspired by the 'bonnet', a traditional Scottish cap that ensure heat stays in the body. 

The device has been under test for two and a half years and with the results so far  encouraging, the financial savings for the whisky industry, and also the Bourbon and rum sectors, could be enormous. 

Named ‘The Scotch Bonnet’, it has been designed and patented by the firm Sangobeg Ltd, who are involved in the whisky industry, and it is currently undergoing evaluation within the trade to gauge its potential.

Director, Ross Morrison, explains the background: “It came about because we’re in the whisky industry. We build maturation bonds, so we see what happens in a maturation bond, and we see how things are stacked. We see that these barrels lose liquid through the wood over time, the famous “Angel’s Share”.

He continues: “It was one of these things. So simple, and we thought, would it work? Because we’ve got a simplified mind on these things rather than being technical experts in the whisky industry, we put it to a couple of guys in the industry. One of them is an engineering director and the other a maturation director at one of the very large distilleries. Their reply was, “Yeah, it might work.”

The next stage in the development was to persuade the industry to trial the device.

Morrison says: “The maturation chap very kindly let us use their test facilities at one of their maturation bonds in Central Scotland. That’s where we’re getting all our figures from”.

“The trials in February represented thirty two months of test, so in December, we will get thirty nine months results. The spirit is legally whisky after thirty six months and can be sold as “Scotch Whisky”, so we  plan to have a blind tasting session with an independent expert just to confirm that there is no difference in taste.

The “Bonnet” is made from fully compressed natural fibreboard. The device is fitted to the top of the whisky cask and attaches itself to one of the hoops on the cask via a set of self interlocking fibreboard modules.

Morrison says: “It doesn’t stop the maturation process, of which the “Angel’s Share” is an essential component, but it cuts down the amount of alcohol being released through the top of the barrel by a significant amount. As the “Angel’s Share” comes out, the top of the barrel become more porous, and as it comes further down, it becomes more and more porous; what this device does is slow that down. In theory it should start working quicker as the barrel with the ‘Scotch Bonnet’ saves more liquid”.

There are normally six casks on a pallet and each cask will have a bonnet fitted to it. The next pallet of six casks sits on top of the first pallet. This action causes the bonnet to provide a seal to the top of the cask. This process is normally repeated with pallets being stored between four and eight high. 

Morrison says: “Two per cent per annum on average per year from Scotch barrels” he says, “But over in Kentucky you could be into double figures per annum. We’ve only done our studies in the central belt in Scotland. We did our thirty two month figures in February this year, and it’s increasing in its savings per barrel”. Our average saving per barrel was 1.6 litres of liquid in that period, but this is Scotland.  What it would save in far warmer climates is the next answer we have to address.”

The Bonnets are durable and reusable, and when placed on another cask, they will start their saving process all over again.

Morrison says: “We now have worldwide patents.  This is not just a “Scotch” thing, it’s for every alcohol that is matured in wooden barrels. It should work for brandy, tequila and rum, and as all of these are matured in very warm countries it should work even better in them.

“It was aimed basically at the Scotch industry because that’s what we work in but as you learn more and more it should be aimed more and more at the bourbon industry and the rum industry, because they mature far quicker. You can get bourbons in two, three, and five years and that’s them gone, so you should be able to save considerable amounts over a short period of time, but I don’t know because we haven’t had any results from any tests yet in warmer countries.

“We’ve now got three major distilleries testing the bonnets. From the one that we’ve had the longest we’ll get our figures and then do the tasting. When that’s done if it’s still continuing to increase in its savings we can then say that we’ve definitely got a very viable product, and we really need to get abroad and speak to the people in the whisky and Bourbon industry as well as the people in the Caribbean about the rum.”

5 December 2018 - Sam Coyne The Drinks Report, editor