Repairing a Tonel

Tonel at Malvedos showing freshly planed staves from a repair early in 2010

Last summer we saw how a small port cask, or pipa, was repaired and re-built at Graham’s cooperage in Vila Nova de Gaia.  But how do we repair one of the giant toneis up in the Douro?

As it happens, one tonel at Malvedos was repaired last summer, but last week Dominic was visiting Quinta do Vesúvio, home of another Symington Port and Douro DOC wine brand, and finding the coopers in the middle of a repair job there, stopped to take these photos of the process for us.

One of the 14,000 litre toneis at Vesúvio was leaking a bit, so the wine was run off into another vat temporarily so the tonel could be repaired.  After careful examination the cooper decided to remove and repair a total of 14 staves.

As you can see in the first photo, the tonel was turned a bit on its cradle and the staves numbered before the hoops were removed and the staves taken out.  Most of the staves just needed a bit of cleaning up and planing, and were set back into place in numerical order.  Small pieces of board have been tacked on to hold them until the hoops are put on again.  The gap is where the replacement stave must be fitted in very carefully. As in the repair of the pipa in Gaia, dried reeds are wedged in between staves and also between the stave ends and the barrel head – you can see the tuft of reeds in the gap for the new stave.

The second photo shows how the end of each stave is notched to fit snugly around the edge of the barrel head.  Again you can see a few odd reed ends sticking out.

The cooper fitted all the old staves back into place, then worked on the replacement stave, planing it down by hand a millimetre at a time.  He was back and forth repeatedly planing a little, testing the fit into the tonel, planing a little more, to get it to fit just right.  You can see the sawdust that’s accumulated as they worked!

Wine in storage – whether in cask or bottle – will throw a perfectly natural and harmless deposit, mostly of tartaric acid crystals.  This deposit can build up in wooden casks, so every two or three years we try to catch all our casks at an empty moment and clean out this deposit.  If it is too thick, it can block the pores of the wood and prevent the micro-oxygenation – the passing through of minute quantities of oxygen – which helps age and give a softened, mellow character to the wine.  Micro-oxygenation works the other way too – the wine evaporates from the cask in what is known as “the angel’s share”, and we would not want to short change our good angels.  Here you can see someone inside the tonel scraping down the sides and shovelling out the deposit.

We actually keep a stockpile of cask parts from all kinds and sizes of casks to use for replacements.  We want Graham’s ports to benefit from the micro-oxygenation that wood allows, but we do not want the wood to influence the flavour of our ports, hence the consistent use of old casks and old wood to repair them.  Last summer whilst visiting Malvedos we tried to peek inside an old house at the top of the quinta; it was too dark versus the glare of sun outside to see anything, so we just stuck the camera in and took a picture.  Lo and behold – we discovered one such stockpile of old cask components, staves, heads, hoops, everything, neatly stored ready for re-use.  Recycling at its best.

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