The principal reasons why relatively few sherry casks are used in the Scotch whisky industry today are availability and cost. Former bourbon casks have squeezed out sherry casks for Scotch whisky maturation due to their plentiful supply and significantly lower price. Of the estimated 18 million casks of whisky currently maturing in Scottish warehouses only some 5% formerly held sherry, and they may cost 10 times as much as ex-Bourbon casks.
However, since buying the Glendronach distillery near Huntly in Aberdeenshire during 2008, Billy Walker and his associates in the Benriach Distillery Co, have been investing heavily in sherry wood – principally Pedro Ximénez and oloroso – in order to boost the reputation of this single malt, which has a long history of ex-sherry cask maturation.
Walker describes Glendronach as more ‘muscular’ than it was under the now defunct Allied Distillers regime, which placed less emphasis on the use of sherry wood in later years of ownership. Around 9,000 casks of maturing whisky were acquired with the distillery, and an extensive programme of re-racking up to 50% of the spirit into fresh oloroso sherry casks has been undertaken, while a ‘pot’ of £5 million has been set aside for the ongoing purchase of sherry casks, underlining how seriously the company takes its maturation regime.
While some new-make spirit is filled into ex-sherry butts, a significant proportion is initially aged in ex-Bourbon casks for a number of years before being transferred into sherry wood for a final period of maturation. A confident and progressive programme of range extensions has taken place at Glendronach, along with several single cask releases. The latest, Batch 8, embraces eight expressions matured in Pedro Ximinez sherry puncheons and oloroso sherry butts.
Inevitably, the style of sherry formerly held in casks is highly significant when it comes to whisky maturation and John Grant, chairman of the independent family-owned Glenfarclas distillery says: “We have experimented with various types of wood and in 1973/74 we filled a dozen types of wood on the same day and put the casks together in the same warehouse.
“From this exercise we decided oloroso sherry gave us the flavours we liked best, and for me using second-fill works better than first-fill casks. You get a nice, full-bodied whisky from the oloroso butts.”
Richard Paterson is master blender for Whyte & Mackay Distillers and is acknowledged as one of the industry’s greatest experts on the use of sherry wood, notably in relation to rare, old expressions of the company’s Dalmore single malt.
“Sherry casks are a way of providing additional characteristics in the whisky that are appreciated by the consumer,” he notes. “But using the right sherry casks is of paramount importance. The Dalmore is a heavy style of malt and works really well with oloroso sherry casks and 30-year-old Matusalem oloroso casks are the optimum. Other sherries don’t have the richness.”
He adds: “You don’t want to lose the characteristic Dalmore chocolate orange style. You have to have muscle and structure in the spirit for it to cope well with sherry, particularly over prolonged periods of time. Oloroso sherry would overwhelm a light, floral spirit.”
