30 January, 2015

Bring us in Good Ale

Steeped in the aromas of a Kilcoole Brewery, Paul Duffy speculates about Medieval Malting and Brewing.

The new IAC premises, as well as offering a commodious office space and views of the foothills of the Wicklow Mountains, happens to stand shoulder to shoulder with artisan craft brewery OBrother. The smell of malting barley and the sound of rolling kegs has brought to mind some interesting features from Balbriggan that may represent the remains of a malting and brewing operation.

I have fond memories of a series of excavations carried out by IAC in advance of the construction of the Balbriggan Outer Relief Road in 2008 and 2009. These excavations uncovered wide-ranging evidence for a previously unrecorded medieval nucleated settlement in the townland of Folkstown Great, Co. Dublin. The settlement evidence occurred about 1.5km to the west of the modern town of Balbriggan and extended across a wide area of low-lying enclosed fields, rising toward a prominent hill to the south-west.

Two medieval stone structures (possibly houses) were excavated fronting a road with ancillary features laid out in linear plots to the rear. The plots seemed to be divided up into croft and toft and shared many characteristics with the medieval vill of Portmarnock excavated c. 25km to the south in 2008. The area to the north-west of these structures was characterised by the presence of an unusual T-shaped kiln and a series of ditches and pits.

The kiln consisted of a stone-lined bowl and T-shaped flue as well as a possible stoke hole, and measured 5.75m northeast–southwest and 5.9m northwest–southeast. Several sherds of medieval pottery (late 12th–14th century) were recovered from the fills of this feature. A significant amount of sprouting barley was also recovered from within the kiln which prompted archaeobotanist Sarah Cobain, to suggest that the kiln might have been involved in the process of malting grain.

Malting however requires the prolonged soaking of grain and brewing requires the steeping of malted grain in warm water. A large, sub-rectangular stone and mortar-lined pit was located c. 40m to the south-east of the T-shaped kiln. It measured 3m in length, 2.2m in width and 1.05m in depth. The lining consisted of mortared stone with a thick layer of compact lime and sand based mortar along the base. The stone lining within the pit suggests it was meant to retain liquid. It is likely to be associated with two further sub-rectangular pits uncovered in the immediate vicinity. Both possessed a lime mortar base but no stone or mortar on the sides.

Evidence for malting and brewing in this period is abundant in the records of several monastic foundations. Kilnhouses and malthouses are mentioned at Duleek, Clonkeen and Grangegorman. The Holy Trinity account roll mentions ‘vessels’ (vasorum) in relation to the kilnhouse at Grangegorman and in 1343 repairs to these vessels required the purchase of lime and tar to the value of 1d and 1d respectively.

Could the ‘vessels’ at Grangegorman have resembled the stone and mortar lined pits at Folkstown Great? The mortar lining would have rendered the largest pit watertight and the two pits with lime mortar linings on their base were also likely to have been constructed to retain liquid. While it was suggested during excavation that the stone lining may have been removed from the two pits prior to their initial backfilling, both pits may conceivably have had their sides clad in wood. Such wooden cladding could have been rendered watertight using a tar treatment. This would explain the significant amounts of lime and tar required for the repair of the vessels at Grangegorman. The “preparing the site of the cistern at Gorman” could recall the construction of such features while these vessels and the Balbriggan pits may be equated with the “troughs for pouring malt” mentioned at Duleek in 1381.

We know from documentary sources that ale was consumed in abundance during the period covering the 13th and 14th centuries yet no major evidence has been discovered to date relating to medieval brewing in Ireland. A single brew in the Balbriggan pit would have produced 1,776 litres, illustrating how the daily needs of any manorial centre could have been easily catered for. These volumes are in-keeping with the average weekly output of the brewers of St. Paul’s in London in the 14th century and, as it happens, match the optimum size for a batch (1600–1800 litres) of OBrother beer in 2015!

Paul Duffy, pduffy@iac.ie

Further Reading
Duffy, P., Cobain, S. and Kavanagh, H. 2014 “From Skill to skill” evidence for medieval brewing at Balbriggan. Journal of Irish Archaeology XXII 59-76.
Kavanagh, H. and Bailey, F. 2010 Final Report of Archaeological Excavation of Development at Folkstown Great or Clonard, Area 2/3 08E054, Balbriggan, County Dublin. Unpublished final excavation report prepared for IAC Ltd.