Sunday, March 18, 2012

Triple distillation in Scotland

Auchentoshan still room
Scotch malt whisky is usually distilled twice in pot stills. There are some exceptions: Auchentoshan and Hazelburn (produced in Springbank distillery) are distilled three times. Benrinnes and Springbank use their own partial triple distillation methods and Mortlach is actually partially quadruple distilled. There have also been some with malt whiskies distilled in Coffey- Stein- or Lomond-stills and recently even a fully quadruple distilled malt spirit from Bruichladdich.

Old Irish pot still at Midleton (
Triple distillation was and is used extensively in Ireland at least from the late 1800's, probably because of a mixture of malt and grain used in big pot still distillations did not give a sufficiently pure spirit in two simple distillations. In early 1800's a common method in Ireland was to divide the product of the wash distillation into strong and weak low wines and then distill them separatedly into new spirits feints and then re-using the feints from both low wine distillations in the next weak low wines distillation. This is actually modified double distillation, which could have been useful especially if the lower cut point of spirit distillation was to be kept quite high, which in turn would have enabled the production of cleaner and lighter style of spirit. During the 19th century as the Irish pot stills were becoming bigger the simple triple distillation was adopted in several Irish distilleries.

It is a common belief that Scottish Lowland distilleries were also using triple distillation at the time, but actually only four or five of the 31 lowland distilleries toured by Alfred Barnard in 1886 were using some sort of triple distillation. Note that just a few distilleries were producing whisky by only continuous Coffey or Stein stills, the 26 others producing at least some pot still lowland malt whisky. Dundashill produced double, triple and Coffey-still distilled whisky and sold them separatedly for blenders. Clydesdale and Greenock produced only triple distilled whisky as probably did Glentarras, too. Glentarras had one wash still, two spirit stills and one feints still, but there are no spesific descriptions of its distillation method, so it is possible that it was just partially triple distilled. Cameron Bridge produced mainly grain whisky, but also "Pot Still Irish" (grain and malt in pot stills?), "Silent Malt" (malt in Stein still?) and "Flavoured Malt" (malt in pot still?), and it is possible that some of these was/were triple distilled. For example Auchintoshan (now Auchentoshan) was double distilling and Rosebank most probably partially triple distilling in 1886. Hazelburn used triple distillation in Campbeltown, but there are no records of triple distillation in the Highlands or the Speyside at the time.

It is not exactly known, when Auchentoshan turned into triple distilling, nor whether in what extent Rosebank has used double, triple and partial triple distillation regimes during the 1900s. One source (Brian Townsend's Scotch Missed) claims triple distillation was used in Rosebank for decades, but according to Ulf Buxrud and the DCL archives partial triple distillation, much in the lines of Benrinnes, was used in the 20th century. Benrinnes has been using partial triple distillation probably from 1954 and Springbank apparently from the early 1900's. The old Hazelburn distillery was operational from 1837 to 1925. It is not known whether they used triple distillation from the beginning, but the spirit stills were quite unique as they had water jacketed tube condenser systems attached to the neck of the both spirit and feints stills (before the lyne arm) and then after the lyne arm the typical worm condensers of that era. These stills probably had very much reflux and consequently the spirit was probably quite light. The new Hazelburn was distilled first in 1997 at the Springbank distillery with "normal" stills.

Auchentoshan uses a simple triple distillation with a very narrow heart cut in the spirit run (82.5 to 80.0 ABV), which produces very light and aromatic whisky.

The Benrinnes distillation system is described in the picture below. Basically the weak feints from all (wash, feints and spirit still) distillations are redistilled in the low wines still and the first part of that is added to the spirit run. This probably adds to the copper contact for the feints fraction.

In Springbank every fifth wash distillation is double distilled as the other four batches undergo a triple distillation. All the feints are added to the intermediate still. The effect is probably much the same as in the Benrinnes system resulting in more copper contact for the feints.

In Mortlach one wash and spirit still produce simple double distilled malt whisky. The rest of the stills produce about 80% of double distilled spirit and 20% of quadruple distilled whisky. The amount of finished quadruple distilled whisky is probably much less as the latter part of the wash (weak feints) is much weaker in alcohol. The weak feints are distilled three times in a small still called the "Wee Witchie"; the first two distillations are blank runs and only solids are removed in between. The third distillation is fractioned in the normal way and the heart is mixed with the product of the other spirit stills. Because the Wee Witchie is small (7 880 litres compared to 17 000 litre spirit stills 2&3), squat and cooled with worm tubs as the other spirit stills, the copper contact is not substantial, but it is possible that the four distillations might change the properties of the feints fraction in other ways, such as successive heating, which might in turn alter the spirit. It is believed that the meaty aromas often noticed in Mortlach whisky are due to the Wee Witchie and the "Byzantine" distillation system, which has been in use from at least 1971.

Mortlach still room, the Wee Witchie at the back (from
Barnard A. The whisky distilleries of the United Kingdom. Birlin ltd 1887.
Buxrud U. Rare malts. Quiller Press 2006.
Morewood S. A philosophical and statistical history of the inventions and customs of ancient and modern nations in the manufacture and use of inebriating liquors. Longman 1838.
Townsend B. Scotch missed. Angel's share 2000.
Udo M. The Scottish whisky distilleries. Black&White Publishing 2006.
Weir R. The history of the Distillers Company 1877-1939. Clarendon Press 1995.