Midleton Distillery


Midleton Distillery image 1

More about Midleton Distillery

Status Operational
Established: 1823
Visitor Policy: Visitors welcome throughout the year
Tel: +353 21 461 3594
Website: http://www.tours.jamesonwhiskey.com
Midleton is one of the largest and most technically advanced distilleries in the world but is also proudly built on tradition and history. Owned and operated by Pernod Ricard’s Irish Distillers division, Midleton produces the Jameson range of whiskies as well as other Pernod Ricard owned Irish Whiskey brands such as Powers, Paddy, Greenspot and Redbreast.


Old Distillery Walk
County Cork
Ireland (Eire)

Jameson and the other blended whiskeys produced at Midleton are a blend of different types of Single Pot Still Irish whiskey and column distilled Irish Grain whiskey. Unusually, all these different whiskeys are distilled, aged and blended at the one distillery – Midleton.

The following is Simon Difford's detailed description of every process employed at Midleton, step-by-step. He spent a week at the distillery researching the following 6,500 words but if you're only interested in a quick overview, then simply read the paragraphs he's marked in bold under the title for each of the processes involved.


Irish 'Pot Still' whiskey is distilled from both malted barley and unmalted barley. Distillation takes place in a series of three pot stills so is said to be 'triple distilled'. The malted barley used is unpeated so no smoky flavours are transmitted to the malt during the kilning process. Hence, the finished whiskey is purer due to the triple distillation and lacks the smoky flavours often associated with Scotch malt whisky.

Pot Still Whiskey - Barley

The Pot Still whiskey produced at Midleton is made using malted and unmalted barley in proportions which vary from 60% unmalted barley and 40% malted to a straight 50/50 split and occasionally a larger proportion of malt. (100% malt would be a Midleton Malt Whiskey and not Single Pot Still Whiskey.)

Irish Distillers sources all the barley and malted barley used at Midleton from Ireland, generally from the South and East of the country where the milder climate, better soil and drainage conditions produce superior quality grain.

Malted barley is so called because it has started to germinate and begun to convert the grain's starch into the fermentable sugars and enzymes essential to fermentation. The barley is encouraged to start germinating by tricking it into thinking that it is spring, achieved by repeatedly steeping the grain in water and draining to allow oxygenation. Germination is then checked before the grain uses too much of the valuable sugars to grow. This is achieved by drying the barley, and unlike many of its Scottish counterparts, no smoke is allowed to come into contact with the grain, so no smoky taste is imparted during this drying process. Even though the fuel used (gas) does not influence the flavour, the way the heat is applied will affect the taste by different degree of toasting of the grain.

Irish Distillers no longer malts its own barley at Midleton but uses an Irish malting company which produces malted barley to its specification. All the malted barley used at Midleton is malted according to the same specification with different pot still distillates using varying proportions of malted and unmalted barley.

Pot Still Whiskey - Milling

The malted barley and unmalted barley are first ground into a fine flour called 'grist' in a process known as milling.

Until the modernisation and expansion of Midleton which started in 2012, a wet milling process was used in Pot Still whiskey production. This involved the grain being steeped and conditioned with hot water prior to milling. In September 2012, Midleton switched to dry milling following the introduction of state-of-the-art mash filter brewing technology. Dry milling uses hammer mills to mill the malted and unmalted barley whilst dry. The flour-like grist produced by the hammer mills is then mixed with water. The coarser grist produced by the old wet mills is needed for processing through a lauter tun however with the introduction of mash filter technology a finer grind is preferable, hence the introduction of hammer mills. The combination of hammer mill and mash filter produces a greater yield from the grain than the old wet milling and traditional lautering system.

Pot Still Whiskey - Mashing

Grist is mixed with hot water in a mashing vessel to allow natural sugars produced from the grain's starch and other solubles required for fermentation to dissolve in the water. This sugary liquid called wort is drained and sent to the fermenters.

The malt and unmalted barley grist is mixed with warm water in a pre-masher vessel and is then pumped, batch by batch, to the mashing-in tank where the first heating stage takes place. The temperature at this stage is suitable for the breakdown of beta-glutens, the cell walls around the grain's starch, in order for the malt enzymes to access the starch and begin converting starch to fermentable sugars. Once the first temperature stage is complete, the mash is then pumped to the mash tun where the full starch breakdown into fermentable sugars occurs. At this stage the temperature is increased to 650C to allow the malt's natural enzymes to react with the remaining starch in the malt grist and starch that's available within the unmalted barley grist to convert both grain starches into fermentable sugars.

This conversion process, at a temperature of 65°C takes about one hour to complete. Then the temperature is raised further to 72°C and held again to allow a final conversion to occur. After the rest period at 72°C a sample of mash is taken and tested with iodine for the presence of starch. If this turns canary yellow then no starch is present, meaning that all the starch has been converted to fermentable sugar. If there is some black showing then starch is still present and the mash will need to be left to allow the last of the starch to be converted. Once conversion is complete the mash temperature is then raised to 77°C before being transferred to the mash filter.

Once conversion is complete the mash is pumped to the mash filter. Traditional mash tuns (Lauter tuns) rely on gravity to drain and separate the wort from the spent grain known as draff. However, the new Mash Filters at Midleton hold the mash between a series of chambers and a combination of pump pressure followed by pneumatic force is used to filter the wort out by squeezing in what is essentially a giant horizontal filter press.

There are four main stages within the mash filtration process: 'filling', 'pre-compression', 'sparging' and 'compression'.
1. Filling – the mash is pumped from the mash tun at 77°C to the Mash Filter. This fills the filter plates with mash so that the mash is sandwiched between different chambers and filter membranes. Wort begins to drain as the filter chambers are filled.
2. Pre-compression – A small compression of the chamber membranes is applied to the thin beds in each chamber until most of the liquid is drained but still leaving some residual sugars remaining in the mash and the filter itself.
3. Sparging – is where the fermentable sugars remaining in the mash, sandwiched in each chamber, are pushed out of the filter through the filter cloth by pumping water at approx. 72 to 76°C (sparge water) into the filter to replace them. The spare volume is split into three batches and at the end of the third sparge all the residual sugar should have been drained from the mash filter.
4. Compression – the final stage involves inflating the membranes in each chamber to squeeze the mash between the filters and so drain the last of the sparge water, leaving a dry bed of draff which is discharged when the filter is opened and then further processed in the feeds recovery area and used for animal feed.

After the mash filtration process is complete (around two hours) strong wort is sent to the fermentation tanks and weak wort is recycled back into the pre-masher with water for the next mash. This helps to maintain strong wort with a high original gravity going to the fermenter which ultimately means more alcohol will be produced during fermentation.

Pot Still Whiskey - Fermentation

Yeast is added to the wort which, over a 2-3 day period, consumes the sugars present to produce an orange-brown beer-like liquid (wash) with about 10% alcohol by volume. When the fermentation process is complete the 'wash' is pumped to the stills.

The strong sugary wort collected from the Mash Filter is pumped into the Barley or Pot Fermenters. Years ago these fermenters were the wooden Washbacks of the type still commonly used in the scotch malt whisky industry. Examples are on display in the Old Midledon Distillery visitor experience across the road from the new distillery. However, the present Barley fermenters at Midleton are state-of-the-art huge stainless steel towers with external cooling coils allowing greater control of the fermentation process and the fermentation of much larger batches.

A proportion of the sugary wort is pumped into a bub-tank and it's here that yeast is added. Known as the 'bubbing stage' adding the yeast to this small proportion of the wort gives the yeast time to become accustomed to the wort's environment and start multiplying its cell number – there is a three-to-four-fold increase in the yeast cell count in the bub-tank. The bub-tank is emptied and the now stronger yeast and wort (known as the 'bub') is pumped into the fermenter with the rest of the wort.

Fermentation begins immediately the bub is added to the fermenter. This is due to the bubbing-stage having removed the lag phase which would otherwise occur in the fermenter as the yeast becomes accustomed to its new environment. As the yeast breakdown the fermentable sugars it produces alcohol, carbon dioxide, water and heat. To prevent the yeast from being stressed or even killed (if the temperature was allowed to rise above 34°C degrees) the temperature in the fermenter is kept to around 28°C by pumping cooling water drawn from underground caverns through the external cooling coils of the fermenters. Fermentation normally lasts about 60 hours, producing a wash with 10 to 12% alcohol by volume.

Pot Still Whiskey - Distillation

The wash is distilled in three pot stills (triple distilled) to produce a final distillate at approximately 83 to 85% alcohol by volume ready for aging in oak casks.

The fermented wort (known as wash) is pumped into the 'cold-wash charger', a large feed-stock storage vessel for the still house. A volume of wash (known as a 'double') from the cold-wash charger is pumped across to the 'hot-wash charger' where it is pre-heated before going on to fill the two wash stills and start distillation.

The old Midleton still house has four pot stills, all the same shape and massive 750 hectolitre capacity. Two are used as 'wash stills' (first distillation) with the other two being a 'feints still' (second distillation) and a 'spirit still' (third distillation). The reason for having two wash stills is because a greater volume of wash needs to be distilled relative to the subsequent feints and spirit distillations. In addition there is a greater level of foaming so the two wash stills are effectively only half-filled to reduce the risk of carryover and contaminating the distillate. The distillate from the two wash (Low Wines) stills fills the feints still. In turn, the spirit produced by the feints still is used to charge the spirit still.

The first distillation, which takes place in one of the two wash stills, extracts alcohol and flavours from the fermented wash without discriminating flavours – it is just about capturing all the alcohol and flavours from the wash. This distillation produces an intermediate distillate known as low-wines. The strength of this varies between 22% and 50% alcohol depending on the way the wash still is operated. Typically for Jameson the low-wines are 43% to 48% alcohol by volume. The residue left in the wash pot still after distillation is sent to be processed into animal feed.

The low-wines are transferred for a second distillation into the feints still where the selection of certain flavours and the removal of others in the final distillate begins. The initial spirits to emerge from this distillation are called the 'heads' or 'foreshots' and these contain the more volatile alcohols. The next spirits to emerge are called 'strong feints' and this is the desirable part of the distillate that will go forward to the spirit still for the third and final distillation. After this, towards the end of the second distillation, comes the 'weak feints' or 'tails' and these contain valuable alcohol so are recycled back to be added to the next batch of low-wines to charge the feints still. The residue left in the pot still after distillation is sent to be processed into animal feed.

The average strength of the strong feints produced by the second distillation is typically between 68-72% alc./vol.. These are used to charge the spirit still where the distillation process is repeated, with foreshots again being removed before the heart of distillate starts to run. It is this 'heart' or middle cut distillate that will go on to become whiskey and has strength of around 83-85% alc./vol.. Lastly, as with the second distillation, the feints emerge – firstly the strong feints and then the weak feints. The weak feints will be recycled back into the feints still and the strong feints will be recycled back in, with the strong feints from the feints still recycled back into the spirit still.

The distiller's art is to adjust the point at which the cuts from foreshots to spirit and spirit to feints are made during the second and third distillations. An advantage of triple distillation versus double distillation is the ability to vary the cuts in the feints still and the spirits still. This allows a constant balance between the distillations to be maintained, affecting the flavour profile of the final pot distillate. Scotch whisky distillers say they get it right the second time - the Irish have a different definition of 'right' and triple distillation produces purer distillate.

To say Midleton produces Pot Still whiskey by triple distillation is a huge simplification of the incredibly complicated process which has evolved. The distillery was built in the late 1970s to make whiskeys formerly produced at several different distilleries, each one using slightly different distillation practices and different pot stills to produce whiskeys with their own very distinctive characteristics. Consequently, changes to the settings of Midleton's stills allow different types of distillates to be produced, mimicking the differences in the former distilleries. This, coupled with the use of different mixes of malted and unmalted barley, allows Midleton's distillers to produce a range of distinctively different pot still distillates.

The mash bill proportions of malted to unmalted barley can be varied. Depending on the grain mix and still settings, three main different types of pot still distillate are produced at Midleton: 'Light Pot Still', 'Medium Modified' (known as 'Midleton Mod Pot' and 'Heavy Pot Still'. Other special distillates such as 'Traditional Pot Still' (a heavier whiskey made by capturing more of the latter part of the distillation run during the third and final distillations) are also produced from time to time. So even before the influence of different woods during aging, there is already a broad selection of different styles of pot distillates for Billy Leighton, the Jameson Master Blender, to choose from.

The folk at Midleton refer to each of these Pot Still distillates by a codes. 'LMP1' is a light-pot distillate made by cutting from spirit to feints earlier in the run, so not allowing as much feinty flavours into the final distillate. 'MMP' is a medium or 'Mod Pot' distillate, with variations such as 'MMP1' being a distillate with a particular cut of spirit to feints, allowing some feinty flavours within the spirit. 'MMP4' is a heavier type of distillate.


Midleton produces all the whiskeys which are blended to make Jameson and its other brands. Various types of pot still whiskey and several different grain whiskeys are made on site in its own stills. Although often overlooked, the grain whiskey element of Jameson is as important as the pot still whiskey.

Grain Whiskey - Milling

The malted barley is ground into a fine flour called 'grist' and separately the maze is also ground into fine flour – both processes use hammer mills.

Both malted barley and maize are used to make Grain whiskey at Midleton. The maize is sourced from France while the malted barley comes from Ireland.

The brewing process used is different to that for pot still whiskey, although essentially achieves the same result – to extract all the fermentable sugars from the starch within the grain. The first stage is to dry mill the maize into flour using a hammer mill. (In 2013 Midleton moved from cage mill to hammer mill to give a finer grind.)

Grain Whiskey - Mashing

The maize flour is mixed with water and heated to liquefy its starch. It is then mixed with the malt grist. The malt's enzymes start to convert the starch in both the malt and the maize into fermentable sugars.

The maize flour is mixed with warm water and heated in a 'high temperature cooking' process where the mixture is continuously pumped through a loop in which the maize is heated to 150°C. This bursts the starch granules so liquefying the starch. This 'liquefaction stage' lasts two to three minutes – the time it takes for the maize to pass through the loop. As it emerges from the loop it is flashed cooled to 63°C.

Separately the malt is ground to grist using a hammer mill and then mixed with water in the malt mixing tank. This watery malt grist is then added to the cooled liquefied maize in the flash tank. (If the malt was added earlier the high temperature cooking process would de-nature the malt's natural enzymes and you'd get no conversion of the starch to fermentable sugars.) When mixed, the malt's enzymes start to breakdown the liquefied starch into fermentable sugar. The percentage of malted barley used is usually around 5%.

The malt and maize mixture is pumped from the flash tank to a cooker converter where further conversion takes place. The liquid flows like a plug down through this converter with a very slow moving agitator stopping material adhering to the sides. The agitator is there to prevent vertical mixing to ensure that each part of the mixture spends the same amount of time in the vessel – around 45 minutes.

A starch iodine test at this stage would show an incomplete conversion i.e. that some of the starch is yet to be converted into fermentable sugar. The mash (milled grain and liquid) is pumped from the convertor through a cooler where it is cooled to 28°C and pumped into a fermenter. A key difference to the pot still brewing process is that the whole mash (grains and liquids) is pumped to the fermenter as opposed to just the liquid. This is because not all the conversion has taken place prior to fermentation starting so the grains still contain starch which can be turned into fermentable sugars.

Grain whiskey - Fermentation

Yeast is added to the partially converted malt and maize mixture which consumes the fermentable sugars present to produce a beer with 13 to 15% alcohol by volume. When the fermentation process is complete the 'beer' is pumped to the column stills.

A proportion of the sugary malt and maze mixture is put it into a 'bub-tank' where the yeast is added. This allows the yeast to become accustomed to the sugary environment and start to multiply its cell numbers before being added to the main fermenter. The 'bubbed' yeasty mixture is added to the fermenter with the rest of the malt and maize.

Fermentation begins immediately with the already converted fermentable sugars being turned into alcohol, water and carbon dioxide by the yeast. Meanwhile conversion of the remaining starch to fermentable sugars continues for the first 24 to 30 hours so there is a slow release of more fermentable sugars during this period. This delayed release of fermentable sugars actually helps the fermentation process as if all the sugars were available at the start the yeast could be stressed by the overly sugary environment.

Fermentation lasts around 90 to 100 hours. The resultant beer produced has a relatively high alcohol concentration of 13 to 15% alc./vol..

Grain Whiskey - Distillation

A continuous column distillation process is used to extract the alcohol and flavours from the fermented beer and produce a distillate that will go onto cask aging and then blending with pot still whiskey.

After fermentation the beer is pumped to the 'beer-well', the column's feedstock holding tank. The alcohol and desirable flavours in this beer are then extracted using three distillation columns - firstly the beer column, then the extractive distillation column and lastly the rectifying column. Each of these columns performs a different role.

The beer column strips all the alcohol and flavour from the beer. When the beer enters this first column it still contains grain solids. During distillation grain particles fall to the bottom of the still from where it is removed for incorporation into animal feed. The distillate produced by this column is known as 'beer column high wines' and is typically around 74% alc./vol..

The beer-column high-wines, which contain impurities such as heavier alcohols and fusel oils are pumped to the extractive distillation column where cleaning of the spirit begins. The high wines enter this second column half way up while water is pumped into the top of the column. The interaction between the rising vapour from the high-wines and the water falling through the column's plates causes impurities to concentrate near the top of the column because they have a greater affinity or bonding mechanism in an alcohol rich environment as opposed to a water rich environment. These top vapours condense and reflux down to a decanter where the fusel oils are extracted before the bulk of the condensate returns to the top of the column.

The ethanol alcohol accumulates lower in the second still in a weaker strength area known as the pinch point. From here the alcohol is drawn off and transferred to the rectifying column. Once the column is correctly set up a balance is achieved which allows the desired level of alcohol and flavour to be extracted from the pinch point. This distillate (the 'pinch') is typically 25% alcohol by volume when transferred to the rectifying column.

The last column, the rectifying column, removes additional fusel oils and some volatile alcohols known as overheads. These alcohols are recycled back into the extractive distillation column so no alcohol is lost from the system. The final strength of the distillate produced by the rectifier is typically 94.4% alcohol by volume.

This three column process operates continuously, only being stopped for cleaning and maintenance. The first distillation column which strips the fermented mash needs cleaning once a week but the second and third columns can run for a couple of months without having to be shut down and cleaned.

A number of styles of grain whiskey are produced using this three column process. The bulk of grain whiskey produced is used to make Jameson. Known as G11 this is around 5% malted barley to 95% maize. This is a soft, delicate, sweet flavoured spirit with fragrant fruity floral aromas which when matured in the appropriate casks produces an ideal whiskey for blending with pot still whiskeys to make Jameson.


The Irish Whiskey Act specifies that Irish whiskey must be aged for at least three years in wooden casks in Ireland before it can be called Irish whiskey. Casks previously containing bourbon or seasoned with sherry and sometimes malaga, port or madeira casks are used for this ageing process.

Oak, specifically white oak is always used to make the casks (not red oak or any other type of timber). This is cut into barrel height logs and then quarter sawn so the tree's rings are at 90 degrees to the plank. Although a very wasteful way of sawing the oak, quarter sawing produces a stronger plank able to withstand the bending necessary to make a cask. The direction of the grain in quarter sawn planks also reduces loss of spirit during the maturating process.

Two types of white oak are used - American white oak and European white oak. American white oak contributes a lot more vanilla sweetness and usually comes in the form of 200 litre barrels previously used to age bourbon whiskey.

Bourbon production demands that the inside of these barrels are charred, a tradition which began in the 1800s when they started to bring casks up the Mississippi. Distillers would buy casks previously filled with anything from apples, flour, wheat and even fish, so to get rid of the smell they burnt the inside of the cask. Not all the American oak barrels used at Middleton are ex-bourbon barrels, a small number of virgin oak (previously unused) barrels are also used but even these are charred. The charring cooks the timber allowing the sugars and vanillins in the oak to be released into the whiskey more quickly than from non-charred casks. Charring also does the following:
1. Burns off wood resins that could contribute to off notes
2. Increases surface area so better allowing sugars, vanillins and other wood constituents to be released into the spirit.
3. Formation of heat degradation compounds that contribute flavour and aroma to the whiskey.
4. Formation of a charred layer plays an important role in the removal of immature character from the whiskey.

Different bourbon distillers specify their own degree of char when ordering casks from their cooperage. Some stipulate a light char, some medium and others a severe char. American law dictates that bourbon must be aged in new charred white oak barrels so U.S. distillers can only use the casks once. Consequently, the American whiskey industry provides a steady supply of ready seasoned casks to distillers such as Irish Distillers. As the casks are already seasoned with Bourbon the folk at Irish Distillers don't have a say in the level of char but most tend to be medium charred.

When buying new oak casks from their preferred Kentucky cooperage, Irish Distillers stipulate a medium char. These 'virgin' American oak casks are used to age whiskey for blends such as Jameson Gold. Virgin casks impart more vanillins, sweetness and tannin to the whiskey than seasoned casks.

The European white oak casks used are merely toasted rather than charred and are mostly 500 litre butts which have been seasoned with sherry or occasionally port, madeira, malaga or masala. These European oak casks have a profoundly different influence on the whiskey aged in them when compared to American oak. The European oak is a different species and has a different composition in terms of lignin, cellulose, tannins and other volatile compounds to American oak. European oak imparts rich dried fruit cake, currant and date flavours.

Over the years the folk at Midleton have built a great relationship with Antonio Paez Lobato, a Spanish cooper and winery owner in Jerez. Antonio makes European oak casks to Midleton's exacting specifications and then seasons them with sherry wine. Billy Leighton and Kevin O'Gorman visit Antonio regularly to see the casks being made, sample the wine used for seasoning them, and even visits the forests in northern Spain where the oak is grown. Ger Buckley, Jameson's Master Cooper is also in regular contact with Antonio to ensure that the casks are manufactured to the highest specification.

All the casks imported to Midleton arrive fully standing (in one piece) and bunged to seal them and also to ensure that the wood stays moist and so watertight. Midleton pay a premium to acquire the best casks made from flawless oak without knots as these have fewer leaks and require little repair. Every cask is inspected by a cooper and nosed when it arrives at the distillery to check for any off aromas caused by secondary fermentations. Any rogue casks are discarded.

The influence of the oak on the maturing whiskey is vital to the flavour of Jameson and other whiskeys produced at Midleton so cask management is taken very seriously. At other distilleries it is common to see empty casks left outside in the rain but at Midleton each cask is cared for like an enthusiast would look after a vintage car - exposing the precious casks to the ravages of the weather is unthinkable. Those of you who have met Ger Buckley will know that he is the resident cask enthusiast and woe betide anybody who harms one of the tens-of-thousands of casks at Midleton under his charge.

Cask rotation ensures that new casks awaiting their first fill and recently emptied casks are quickly filled to ensure they don't have a prolonged period lying empty. The longer casks remain empty the more they deteriorate so at Midleton they ensure casks are filled within one to three months. New sherry butts and port pipes are filled immediately they arrive at the distillery, some 75-80 casks at a time. The increased urgency to fill these casks is due to the risk of secondary fermentation of any wine remaining in the cask and the desire to retain characteristics from the wine used to season the casks.

Computerised cask management tracks every cask and its contents but a mark on each cask is also displays its fill number. As American barrels pass through the filling station an inkjet applies a mark indicating what number filling it is - B1 indicates a first filling, B2 a second filling and B3 is a third filling. A similar system is used for sherry butts and port pipes with colours indicting the fill - blue for first filling, yellow for second and white for third.

American oak casks are usually filled and emptied three times. Every time you refill a cask it contributes less to the whiskey. Consequently, after three fillings some distillers recondition their casks for further use by scrapping the inside to reveal fresh oak and then re-charring. The folk at Midleton buy new casks rather than recondition and after three fills (or less if they feel the cask is getting tired) sell the used casks on, mostly to the rum industry. (Given the U.S. embargo did you ever wonder where Havana Club sourced its ex-bourbon barrels from?)

Triple distillation causes Midleton's pot still distillates to have a higher concentration of alcohol than double-distilled Scottish malt whiskeys - typically 84-85% alc./vol. while the grain spirit is 94.4% alcohol by volume. Water is added to the distillates to reduce their strength to 63.5% for Pot Whiskey and 70% for Grain Whiskey, the optimum strength to ensure a balanced wood extraction whilst also keeping the number of casks to a minimum.

The water used to dilute the distillate to casking strength is taken from the municipal supply and processed through reverse osmosis to purify and ensure a neutrality that won't influence the whisky's flavour.

Casks are filled through a bung hole in the head, rather than the middle (the bulge) as is traditional. They are also emptied by sucking from the top of the cask. Casks are filled and emptied without removing them from the pallet on which they sit, so may stay on the same pallet for over thirty years during which time they might be filled and emptied three to four times. Midleton fill some 1,700 to 1,800 American barrels a day with an additional filling line for Sherry Butts and other European casks operated as required.

Over the past 20 years Midleton have converted all its ageing warehouses from being racked to palletised. Six casks stand on each pallet and these pallets are stored seven high in the warehouse - the strength of the bottom casks able to support the weight of all the pallets and filled casks above. Palletised warehouses allow more casks to be stored in the same space and virtually eliminate the need for manual handling as forklifts do all the work. Palletised warehouses also reduce the movement and rolling of casks and hence are more 'gentle' on the casks reducing hoop and stave damage.

Midleton has warehousing on site and also 12 kilometres away. The warehouses are built to a very high specification with extra thick external walls and a dividing wall splitting each warehouse into two sections, cell A and cell B. Thus warehouse 31 is divided in 31A and 31B so should a fire start it will be contained within one cell and extinguished by the automated sprinkler system.

Alcohol loss through evaporation, or 'Angel's Share', averages just 2% compared to some ten times that in the tropics. Ireland is not a hot country so there is little difference in temperature and so speed of maturation between the warehouse floor and roof. Consequently there is no benefit from moving casks from the bottom to the top of the warehouse and vice versa as is practiced by some whiskey distillers in Kentucky. Once a cask is placed in a warehouse at Midleton it usually stays in the same place until ready to be emptied.

Occasionally, whiskeys are blended and then put back into cask for a final finish period - usually six to 12 months and this is decided by the Master Blender, Billy Leighton.


Blending or 'vatting' is the final part of the process where aged pot still whiskeys and grain whiskeys are mixed and married for anything from two days to a month before bottling.

The distillers and blenders work together to decide what type of spirit to age in what type of cask - European oak, American oak or virgin oak, and first fill, second fill or third fill casks. The whiskey will then be left to mature for a number of years. How many years is decided by how that whisky matures, but if the bottled whiskey carries a 12 year old age statement then all the whisky in that blend will have been aged for at least 12 years.

It falls to the Jameson Master Blender, Billy Leighton, to select casks containing whiskeys with the particular characteristics required to assemble a blend to match a particular Jameson expression. The Jameson brand comprises of a family of whiskeys, each member of this family having a different maturity and style. However, as with all families, certain character traits run through the Jameson family to a greater or lesser degree - perhaps most noticeable are the fruity peach and apple flavours from the barley and Jameson's signature soft, almost creamy mouth feel.

The grain component in Jameson blends contributes sweeter notes with vanilla coming from first fill bourbon casks. This sweet vanilla profile runs through the Jameson range with charred oak casks imparting an earthy element that compliments the spicy, aromatic oily character that pot still whiskey brings to the blends. All Jameson whiskeys have a complimentary action between the soft estery aspects of the grain component and the more fruity spicy heavier flavoured pot still whiskeys that are fundamental to the brand.

Standard Jameson is blended using a particular style of grain whiskey with a style of pot still whiskey known as mod pot' and some of this is aged in Spanish sherry butts. However, other whiskeys in the Jameson range use a light-pot or mixture of light-pot and mod-pot. The style of whiskey and cask type used depends on the robustness and flavour notes that form particular whiskey blend.

The challenge for the blender is to produce consistently tasting blends year after year by a combination of stock management and cask selection. The Master Blender must have an intimate knowledge of his stocks and know what whiskeys are available, in what quantity, and when they are expected to reach the desired level of maturity. Blending is not all just about standing in a lab sniffing, tasting and assessing samples. Billy Leighton neatly sums up the challenges of being a Master Blender when he says:

"You've got to have a 360 degree view of what's happening in the business with your brands, you have forecasts coming through from the markets for the demand for each brand into the future and its the blender's role is to ensure that there's stock available on an on-going basis to fulfil the demand that is coming through for all the brands. So you're looking at brands that maybe five years old, you're looking at brands that may be 18 years old and you've got to be careful that you don't use up all your stock in your five year old and leave you nothing behind for your 18 year old. So a lot of the work is stock management and even on from that, when you are looking down the road at what the demand is that's coming towards you, youve got to have some input to what the distillery is actually producing, in the split of spirit types that are being produced, making sure that spirit has been filled into the correct profile of casks."


Tankers bring the component whiskeys from Middleton to Pernod Ricard's bottling facility at Fox and Geese at cask strength, between 60 - 68% alcohol by volume. This is pumped into component storage vats in the lower vat house, an area affectionately known as the lounge from the days when the drivers who delivered cases of Jameson around Dublin returned from their rounds and relaxed with a whiskey.

Of the twelve wooden vats occupying the 'lounge' today, two were manufactured in 1833 by Charles Carty of London for John Jameson & Son's. They were used at Jameson's bow street until 1971 when they were dismantled and reassembled where they currently stand, and have been in daily continual use since. They carry the name of the cooper who made them, Thomas Taylor. He joined Carty in 1823 and a copy of his apprentices' contract outlining the very strict terms and conditions of his employment is displayed on one of the casks. "He shall not commit fornication nor contract matrimony in the said term, he shall not play at cards, dices or tables or any unlawful games where his master may have any loss."

Each Jameson whiskey blend has a recipe specified by the Master Blender, and like following a cake recipe, the components are blended together according to that recipe. Once blended the high strength whiskey is reduced to bottling strength by blending in water purified by reverse osmosis. Lastly a tiny amount of caramel spirit is added to standardise the colour of the bottled whiskey. This small amount of colouring doesn't affect the taste, it just standardises the colour so that when bottles appear on the shelf they are all the same shade of amber. This is necessary because depending on the tannins in the cask and how many times each cask has been refilled, they produce whiskey of slightly different shades.

After blending the whiskey is cooled to approximately 0°C before being pumped through cellulose filters. Known as chill filtration, this process removes fine particles of barrel dust and char along with fatty acids which might cause the whiskey to turn hazy when cold. This processes 80,000 litres of whiskey per hour and from here the filtered whiskey is pumped to the bottling vats.

The onsite lab carries out final product checks before the whiskey is pumped from the fifteen bottling vats to the bottling hall where six bottling lines each run at some 180 bottles per minute. Each brand of whiskey has numerous different labels according to the language and regulations of various export markets. The hundreds of different labels required are stored in a humidity controlled room so the labels retain a certain level of moisture which makes it easier for the labelling machine to apply to the bottle. Robots pack the bottles into cases and palletise for distribution around the world.

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