Sunday 12 January 2020

Let's Talk Recharring: STR Casks

Hi everyone,

We are back! New year with plenty of exciting and innovative stuff going on.
I haven’t done any of these Let’s Talk pieces for a while (the last was 2 years ago now!) and I’m really interested to see what you guys and gals think.
Once again, I am not a chemist or biologist and could very well be full of crap.

Anyway, the topic I’d like to discuss today is the phenomenon known as STR.
Now, you may be thinking; ‘what kind of hideous new sexual transmitted disease is that?!’

In fact STR stands for ‘scraped, toasted & recharred’ and has started being used at certain connected distilleries; Kilchoman, Kingsbarns, Nc’nean, Cotswolds, Penderyn, Kavalan and Gouden Carolus as well as plenty of others that don’t use them for specific releases.
The connection? Dr Jim Swan.
The rejuvenation of casks is not a new thing. People have been recharring casks for a long time now. These have been Bourbon barrels, hogsheads and some Sherry casks. This was essentially to get a few more uses out of the wood.
Though, there was (a now banned practice) of recharring the wood and then quickly dousing it with Paxarette Sherry, which would of course seal quickly into the pores of the wood.

What changed?
Jim Swan (or at least he is usually credited) came up with the brilliant idea of using old red wine barrels, that, when recharred, gave a new flavour that had not really been seen before. It wasn’t too intense or restrained, and, very importantly, it gave young, immature whisky a more mature flavour at a young age.
This was exactly what he needed, as the distilleries that he was involved with were generally newer distilleries and new builds that didn’t have a lot of time on their hands before needing to get product out on the market.
In addition to this, Sherry casks and other fortified wine barrels were becoming much more expensive, while Bourbon barrels don’t necessarily give you the punchy, fast maturation that they were looking for.
Their question to Jim was; ‘is it possible to create a mature, smooth, nice whisky at 3 years old?’
He could pretty much smile and say; ‘yes… I invented it.’
(Though I feel I should point out that Glenmorangie also used recharred wine casks for their Milsean release, though these weren’t referred to as STR casks.)

So, let’s talk a bit about STR casks and what they mean for the flavour of the whiskies using them.
I have a feeling that we’ll be seeing more and more of them…

First, let’s have a lot at what people were doing before; recharring casks, but not wine barrels.
I have been lucky enough to visit Loch Lomond distillery and actually see a cask being recharred and it was a great education.
This is usually a process reserved for older barrels that have been used a few times and lost a lot of their flavour. When this happens, the recharring can be used to rejuvenate the cask and bring a lot (though not all) of the flavour back to the barrel.
The barrel has the cask ends taken off and a machine will go around the inside of the cask with a wire brush or mechanical shaver. It is then transferred to a charring machine with a large gas flame and the charring is pretty much the same as any other charring that you can read any number of other articles about online.
I was surprised how long this charring went on for at Loch Lomond though. My expectation was maybe 30 or 40 seconds of charring but this went on for minutes. About 2 minutes, 45 seconds.
My understanding is that this process cannot be repeated over and over though, because the wood is thinned by each scraping and the barrels would then leak.
Anyway, as I said, this has been done for a long time. Talisker Dark Storm being a good example.
The recharring should caramelise the sugars in the untouched wood underneath the penetrated layer, giving more classic oaky flavours like caramel, toffee and vanilla. However, these will not be quite as intense as a virgin oak cask because there are some flavour chemicals that do not rejuvenate.
In particular, it looks like the Oak Lactones do not rejuvenate in the recharring of a cask, leaving you with less spicy and coconut flavours (Thanks again Whisky Science). In addition, I’ve found that there can be lower levels of tannin in recharred casks.

Some recharred Sherry casks have also been popping up, particularly from Springbank and Kilkerran.
Weirdly though, these whiskies are usually dark in colour and look very similar to whiskies that have spent time in 1st fill Sherry casks. Having tasted the new Kilkerran 8yo Cask Strength, I would say that this also fits with the flavour profile created. Blind, I am not sure I would be able to tell the difference between something matured in a recharred Sherry cask and a 1st fill Sherry cask.
This could be to do with wood thickness. A Sherry cask’s staves are much thicker than a normal barrel and Springbank could be recharring these casks only lightly. A combination that would encourage the Sherry that has penetrated deeper into the wood to be more assessable to the whisky that then goes into these casks.
I asked a friend of mine who works for them and he said that the casks are lightly recharred, which seems to agree with what I suspected.
Okay, cool. So that’s what has already been going on. But what about this new thing? Why use ex-red wine barrels to rechar?

Well, people disagree on this next bit.
Some say that the recharring penetrates only so far into the wood, leaving some of the wine in a layer that is still accessible to the whisky.
Others disagree and say that the recharring destroys the wine in its entirety, but the caramelisation of that wine does give a different flavour.

Unfortunately, I do not have exact measurements of where the wine can penetrate into the wood compared to whisky but we know that wine is more viscous and dense than whisky and therefore not penetrate quite as far into wood that is originally toasted rather than charred.
However, the main evidence for myself is flavour and colour.
If there truly was wine untouched in these STR casks, then the whiskies matured in these casks should taste (even slightly) winey with red fruit notes. This is not something that I have found in whiskies matured in STR casks. Though I would be interested to know if anyone else has? The colour of the wine would also be expected to come out into the whisky, giving it a slightly redish hue. Again, I have not seen this in the whiskies that have used these casks.
Instead, what I have seen and tasted, is whiskies with more oaky flavours and a dark bronze-y colour similar to Bourbon.
As you can tell, I firmly believe that the wine caramelises and is destroyed inside the wood during the recharring and THAT is the difference in flavour from traditionally recharred casks.

Though this does depend on what the distillery that is buying the casks has asked for. These STR casks are being made by cooperages and they can make them to order. If you want something more or less heavily recharred or toasted or scraped, they can do that.
This gives the option for huge variation in these casks and is exactly what these distilleries want.

So there are two good reasons that new distilleries are using these casks;
Firstly, for the good amount of ADDITIVE flavour coming from the oak and the caramelising of the wood sugars and red wine, giving caramel, toffee, vanilla with fresh fruity hints like peaches and apricot.
Second, the excellent SUBTRACTIVE maturation of these casks from the new and active layer of charcoal in the barrel. This helps the cask to take away harsher flavours and off notes from the new make that is put into them. Of course, for whisky that you want to taste good in only a few years, this is a big bonus.

The red wine being used here is mostly Portuguese and Spanish red wine with some French in the mix. However, because the wine is caramelised in the recharring, it matters very little what type of red wine that this would be in my opinion.
The oak type tends to be exclusively American Oak, though I am sure some have experimented with European. The use of American Oak may be just because it is cheaper and easier to hold of, or also because European Oak is generally more porous and would leak after being scraped to the same level.
These barrels are Barriques, which means that they should be about 225-230L.

Well, that’s how they are made and what flavours you might get with STR casks but the other thing I would like to talk about is whether using these casks is a good thing or not.

Different cask types are being looked at all the time and the SWA’s decision to allow a bunch of new types I think was very positive and forward thinking. Bourbon, Sherry and Hogsheads are very much the old guard and consumers are looking for whiskies that are different, new and interesting.
STR casks fit into this modern whisky scene very well. They give a different take on the classic flavours of a distillery you might know well.
What worries me is this… If all of these new distilleries are using these STR casks, won’t they all taste a bit the same? Is this starting to be a case of lazy whisky maturation?
With Bourbon whiskey, they have to use virgin oak casks. It’s the law. But it does make things a bit dull in my opinion and Bourbon has had to adapt to give consumers new things (long ageing, weird finishes, sending the whiskey out to sea, etc). These STR barrels have the same kind of flavours, just not quite as harsh or spicy. By using these, yes, you get a 3 year old whisky that tastes fully matured but you also aren’t truly engaging with the character of the spirit that you are trying to make. Instead, you’re just covering it up.
But then, when you don’t use them, your whisky can taste harsh and unmatured.
Really, there’s no right answer.
Apart from, I guess, leaving your whisky to mature for a decent amount of time before releasing it… but then, you’d likely be bankrupt by then!
Remember that we live in an age where distilleries are struggling to keep up with demand and are discontinuing traditional age statements in favour of younger whiskies. STR casks are a tempting option for distilleries that are looking to make their younger malts taste more mature, essentially tricking us all into thinking that they are older than they are.
Again, not necessarily a bad thing as long as it is done carefully, and with quality in mind.

Anyway, I hope that this has been useful to you!!
What do you think? Have you tasted an STR matured whisky and been disappointed or surprised? Have you had your mind blown by a recharred Sherry Springbank? Or are you worried that STR casks will take over the maturation of young whisky? Let me know!

1 comment:

  1. Hi Dave - this is a very insightful article into recharring the technique and the benefits for aging whisky. At Barrique-Plus we have developed a different technique for reconditioning oak barrels, which I would like to hear your thoughts on. Feel free to get in touch. best regards, Torsten (