Sherry-seasoned casks have long been used for Scotch whisky maturation. But until recently there was little scrutiny of the practice. Many ‘sherry’ casks used to age whiskies advertised as such never saw genuine wine. Kristiane Sherry explores the industry’s open secret.

There’s a wealth of misinformation about sherry casks used to age whisky. Pre-2015, when the Consejo Regulador introduced a sherry cask seasoning accreditation programme, there’s little to no way to guarantee that real sherry was used to season casks. The word sherry conjures up thoughts of oloroso, amontillado, Pedro Ximénez, and others. But wines used to season casks are not the same as the classic styles that are bottled commercially – and may not be certifiably sherry at all. It’s an industry open secret. And it goes against the fundamental truth that consumers deserve to know what oak their whisky was aged in. For whiskies filled into ‘sherry’ casks before that time, producers cannot give that assurance.

Bodegas Estevez

Sherry maturing at Bodegas Estevez – casks like this are very rarely used for ageing whisky

Sherry seasoning: a brief history

Sherry must be made in a specific region known as the Sherry Triangle just outside Jerez de la Frontera in Andalusia, Spain. It’s made to strict standards which depend on the style, and this is overseen by the Consejo Regulador of the Denomination of Origen (think: the Scotch Whisky Association of sherry). Central to the production requirements is the way sherry is matured in warehouses – and its this evocative imagery that Scotch producers often align with when they market their sherry cask matured whiskies.

Beautiful old barrels line warehouse walls, stacked high in solera systems. These are complex networks of fractional blending and maturation casks. New wine is added to the ‘top’ after wine is taken out of the system from the ‘bottom.’ Within the systems, casks will be part-emptied and refilled at intervals depending on the style of sherry being made, but always with some older wines remaining in each barrel. The casks that make up these systems will have been used for decades. And while they are hugely valuable to a bodega, because they have been used many, many times they would add very little to a new spirit. 

This has been the case for centuries. Sherry was blended in soleras and the mature product was shipped in transport casks for export. For Scotch producers, this was incredibly convenient. Sherry would arrive from Spain, the transport casks were emptied for bottling, and instead of shipping the empty casks back, they would be used to age Scotch whisky. Until 1986.

A sherry cask shortage

With the accession of Spain to the European Union, it was required that all sherry must be bottled in Spain, and transport casks disappeared overnight. This marked the significant boom in contract sherry cask seasoning. “It’s standard practice, and has been for some time, for bodegas to season casks on behalf of Scotch whisky producers,” one well-placed industry source, who asked to remain anonymous, told me.

At one point, this involved spraying a substance called paxarette, a concentrated wine, on the inside of casks. It was used to mimic the effect of the sherry. This widely used but often frowned-upon practice ceased with the Scotch Whiskey Act 1988 (enforced from 1990) which stated nothing could be added in the whisky-making process except for caramel colour. (There is some debate that the Act doesn’t stretch as far as paxarette – but that’s for another time.)

The problem is that, until the Consejo introduced a sherry cask seasoning accreditation programme in 2015, there was little to no guarantee that casks were being seasoned with a liquid that met the requirements to be called sherry.

But is it actually sherry?

“I have heard of that happening,” whisky consultant and broker Blair Bowman states, referring to the practice of non-sherry compliant wines being used to season casks labelled as sherry. “Not in the cask brokering world, but the wood brokering world has some dodgy characters.”

Another industry source spoke to me off-record and said pre-2015 he visited an industrial winery close to the sherry region. “It produced ‘sherry’ seasoned casks for some big Speyside distilleries, but it doesn’t sit inside the Sherry Triangle,” he said, adding that the provenance of the grapes was extremely questionable too. “I can imagine everyone was as guilty as each other. It was an accepted practice. You’d need a hell of a lot of old barrels and the right conditions, which aren’t the easiest things to suddenly create.”

He continues: “Quite often those guys will have a more legitimate sherry bodega – having the name lends credence to the more industrial side of the operation. They aren’t going to use their ‘proper wines’ just to season a cask.” Instead of the rich, characterful, aged quality of sherry wines, these ‘improper’ wines are typically thin, young and very intense. “They’re more or less undrinkable, the ones I’ve tried.”


Doug-McIvor from Berry Bros. & Rudd

Mysterious casks

Berry Bros. & Rudd’s reserve spirits manager Doug McIvor weighs in. “You don’t always know the history of every single cask,” he says, especially from the 1960s up until the mid-2000s. “No-one really knew because there wasn’t much provenance around the wood.” It’s one of the reasons he only sources whisky in cask from a few trusted suppliers. “As a firm, I don’t think we’ve got anything to worry about.”

Have things meaningfully changed post-2015? Another source particularly well-versed in finding suitable casks is confident things have changed. “There has been a big push from a number of companies to have the [cask] certification from the Consejo. What you’d find in the past is that the wine wasn’t even coming from the area and was shipped in. Now there are regular audits. At least two a year into the premises. It’s very well controlled from what I understand.”

‘Sherry’ casks filled pre-2015

Evidence strongly suggests that practices have changed. With the new certification system casks are now being seasoned with legitimate sherry – though it’s still very unlikely to be a mature wine that would be sold commercially. But in the world of Scotch whisky, seven years is not long. Many entry level age statements start at 10 or 12 years, which means the youngest components would have entered cask in 2012. And that’s presuming it’s a first-fill ex-’sherry’ cask. As is common practice in Scotland, casks are often used multiple times.

“You also have to consider that casks will be seasoned for up to two years with the certified or non-certified wine,” the source continues. “It could be 2027, 2028, 2030 before we see a 10- or 12-year-old single malt product with guaranteed sherry cask provenance. That’s the timescale and the issue.” And even in this new era of greater transparency, “there’s no way to be sure, unless you can visually see the QR code on the casks,” he says.

“I think it’s about pure honesty,” McIvor says. “People just want to know as much as they can about the product.” He succinctly sums up the problem. It’s reminiscent of the much-reported practice of some Japanese whisky producers blending locally-made liquid with imported Scotch – and still being sold as Japanese whisky. The issue here isn’t necessarily that ‘sherry’ casks haven’t been seasoned with improper wines. It’s not even fundamentally a quality issue – we’ve all drunk these whiskies, and likely enjoyed them. It’s about misleading consumers. No companies have acknowledged that their sherry cask-matured whiskies aren’t being seasoned with actual sherry. “It’s about transparency, honesty and building trust with the consumer,” McIvor says. “That’s what we want to do.”

Representatives from Edrington, Diageo and Chivas Brothers have been approached for comment.