The coopers at Kavalan employ a shave-toast-rechar (STR) process to prepare barrels destined for the production of Kavalan Solist Vinho Barrique. Both red and white wine barrels await their fate - this modern kit is state-of-the-art and devastatingly efficient.
A barrel is mounted horizontally on to a contraption that restrains and manipulates it during rejuvenation. The shaving device has a protruding arm as deep as a cask, ending with a menacing-looking thick, bladed, steel cog. Two powerful drive belts whizz the cog into a blur. The whole apparatus is mounted on to an extending arm that runs up and down the inner staves, stroking the oxblood red lining in 10cm strips. The rollers twist the cask round clockwise by a cog-width, enabling the noisy blades to cut on both passes - in and out. It's a burring, vibratory, repetitive process. A mound of two-tone, coiled wood shavings accumulates in the base of the cask, sliding down the curved staves with every clockwise rotation. When the cask has been completely shaved exposing the new wood, the cask is tipped up and the shavings trickle out.
Toasting a cask involves a distance exposure to heat. This breaks down the wood structure in the uppermost layers promoting flavour development. Charring is the direct application of flame to form a char layer, which helps to mellow the spirit. Elsewhere, coopers light small gas burners inside barrels to toast them - Kavalan do things more consistently. The toasting apparatus looks like a washing machine fashioned by Mad Max, with a jutting out heating element encased in a hard cylinder of perforated sheet metal bolted on to the front. This penetrates the inside of the cask, the heater is set to 250°C, and the cask begins to rotate briskly. It's left to spin and toast, making a full rotation once every 22 seconds.
The final part of this three-act structure is charring. Before the cask is ignited, a metal hoop is inserted into the lip of the cask to protect the groove cut for the cask head. Then the gas burner is lit and its blackened, hooded head is nudged inside the rotating cask spewing flames. The staves catch alight, generating an immense wall of blazing heat. Flames shoot skywards; a fiery geyser erupts through the bunghole and great balls of rich red and deep orange roll up from inside the mouth of the circular inferno. Staves crackle amidst the billowing flames. This wheel's on fire - we watch it burn.
After 65 seconds, the cooper discharges a power spray and douses the flames' ardour with fine jets of water. Instantly, the brightness is vanquished and clouds of dirty white smoke puff from the extinguished cask forming an impenetrable column that rises up into the high roof space. With a hook, the protective metal hoop is extracted with a clang, and the cask is left to cool. Once the smoke clears, the interior is shiny black, the crazy cracked char patterns visible on the blackened surface of the wood. Now the STR cask is ready for filling.