In each issue of Unfiltered, we seek out the definitive explanations to your burning  questions on all things whisky. Back in 2009, we shone the spotlight on sherried whisky with the help of Willie Phillips, former managing director of The Macallan and former chairman of the Society

Willie, tell us, why do some sherried whiskies have sulphury notes?

A: Sulphur may be burned to make sure there are no foreign organisms in the cask between fermentations of new wine in the process in Spain. Sometimes you can get too much of it – if you do, the cask shouldn’t have been passed for filling and it won’t be the best in my opinion!

Q: Why did whisky makers first start to store and mature in sherry casks?

A: Sherry casks were first used because they were available from places such as Bristol, Glasgow and Liverpool when Spanish producers shipped over bulk loads of sherry into the UK.

Q: Have sherry casks become harder to get hold of and has there been a change in the way they are used?

A: When the Spanish authorities made a rule that all sherry had to be bottled in Spain, casks ceased to be so easily available in the UK. A small number of distillers had to buy new casks in Spain from oak grown in the north of the country, in Asturias and Galicia. The staves are taken to Jerez for seasoning in the warmer atmosphere and fabricated into casks. Then they go through one or two new wine fermentations, before being filled, as part of the Solera system, with amontillado or oloroso. So, it may take four to five years to prepare a sherry cask, whereas before you could pick them up ready to be used.

Q: When were sherry casks first used?

A: I can’t say exactly, but there was a Macallan orderbook with an order for a cask of Macallan dated 1890.

Q: Is there such a thing as an optimum age for a sherried whisky? Are older ones always better?

A: I don’t believe there is an optimum age as such. The older a whisky gets, the more likely it is to get a bit ‘woody’. It depends, of course, on the original quality of the cask and the conditions of maturation – for example, if a cask has been in a dusty warehouse, I can usually smell that.

Q: Is it true that originally the casks the distilleries got from the sherry producers were inferior casks made solely for transportation purposes?

A: So far as I know, no. Sherry producers shipped good product in older, but sound, casks over to the UK – they were not inferior, the casks were simply no longer of use in the bodega system. After coopering, they were sound for another 20 years in Scotland.

Q: Some people don’t like sherried whisky – what would you say to encourage them to try it?

A: In my opinion, maturation in sherry wood enhances the whisky flavour. Some might feel it disguises the whisky flavour – I personally don’t.