It’s a quest for distillers and blenders which they refer to as wood management, wood policy or cask selection. But the meaning is the same, sourcing the finest casks on a consistent basis. One option is ordering directly from distilleries and wineries. Another is commissioning a cooperage to produce and season casks according to a distiller’s specification.
Toneleria del Sur based in Montilla-Moriles in southern Spain offers distillers an extensive range of cask types under the Casknolia brand name (launched in 2014). This includes Casknolia Virgin (unused American and European oak casks), Casknolia Historic (pre-used American oak casks), and Casknolia Legacy which is an ‘a la carte’ service giving distillers exactly what they want.
“I tell my clients what all the options are, the choice of oak types and char levels, the various styles of sherry and Spanish wines from different wineries which can be used to season the casks, and they can decide on each detail of every cask,” says Rafa Cabello, Toneleria del Sur’s export manager. Now 39, he’s held this post for seven years, having trained as a cooper at Toneleria del Sur from the age of 14.
“It takes five to six years to train, making staves, heads, hoops, and knowing all the machinery. The greatest amount of time is spent learning about charring the interior of casks, and the most difficult part of a cooper’s training is to understand the oak. Using a hammer is practise,” says Rafa Cabello.
Starting young was hardly surprising, as Rafa’s father Rafaello began training as a cooper at the age of 12. Aged 24 Rafaello established his own cooperage, in 1974, initially supplying casks to wineries. Rafaello is now CEO of Toneleria del Sur, and supplies whisky distilleries around the world.
Most casks produced at the cooperage are American oak, which caters for single malt demand. Some are French oak, while demand for Spanish oak casks is growing around the world.
Spanish oak is sourced from Cantabria and Asturias in the north, with suppliers that practice sustainability selecting trees 80-100 years old. The oak is subsequently air-dried, which lowers the moisture level from 70 per cent to around 16-17 per cent after 18 months.
“The flavour from Spanish oak is very different to American oak which is very sweet, French oak is slightly sweet, and Spanish is in the middle providing medium sweetness,” says Rafa Cabello.
The extent of a cask’s influence is also determined by size. The smaller the cask the greater the amount of liquid (proportionately) is in contact with the oak surface, from which the maturing spirit extracts flavour compounds. This explains why more distilleries are exploring and utilising variously sized casks, particularly smaller specimens. Casknolia’s repertoire starts with a 30 litre cask, and continues with 40, 50, 64, 100 and 130 litres. Among the more typical sizes are 200, 225 and 250 litre casks, culminating in a 450 litre puncheon (similarly sized to a butt, though shorter and rounder).
Charring (i.e. burning) the interior of the casks is a vital part of the process, using a naked flame to create a surface layer of char. The intense heat also toasts a layer of oak beyond the char, causing flavour compounds to break down into smaller groups and become ‘flavour active’ (having been ‘dormant’).
A range of charring levels begins with a number 1 char, classified as light, number 2 is medium, number 3 is heavy and number 4 extra heavy. Most casks at Toneleria del Sur are number 3. The longer the process the heavier and deeper the char layer, and the deeper the toasted layer beyond. Each char level promotes particular notes, with a number 2 for example characterised by coconut and hints of vanilla, while a number 3 features smoke and vanilla.
Some cooperages use gas to provide flames for charring, but Toneleria del Sur burns remnants of oak.
“Controlling an oak fire is much harder than using gas, you can’t just turn the flames up or down, and you need a lot of experience to judge when a particular char level has been achieved. This is because every cask is individual, the level of moisture varies for example, and you must understand the density of the pores which varies among different types of oak, so it’s not just a case of working to the same time frame,” says Rafa Cabello.
Casks can subsequently be seasoned, with Rafa acting as a master sommelier explaining all the available wines, including different styles of sherry, wines outside the sherry designation, and organic options. Rafa also takes distillers to wineries in Jerez, Malaga and Montilla-Morilles to taste samples before they decide which to use.
“PX casks for example are fantastic for maturing whisky, but PX will not be the same from different wineries, as the level of sweetness can vary enormously,” says Rafa Cabello.
Casks reside in the relevant winery for the seasoning period, typically 12-36 months. Prior to departure, casks are emptied but receive one for the road, of whichever wine was used for seasoning, in order to remain hydrated and fresh en route to distilleries in 32 countries. This includes Zuidam in the Netherlands, High Coast in Sweden, Kyro in Finland, Paul John in India, as well as Rabbit Hole and Westland in the USA. But it’s not only casks that are exported – Rafa Cabello was too.
“I wanted to understand more about distilling and spent two months at Westland making whisky with Matt Hofmann (master distiller) and learned a lot. Matt explained the industry to me and how I could help,” says Rafa Cabello.
We’ll also be able to learn more about the work of a cooper, as Toneleria del Sur will begin constructing an additional cooperage next year, dedicated to the Casknolia range, together with a visitor centre. Completion is projected within three to four years, and whenever that is I want to visit on day one.