Production

The silent season

A distillery's year comprises more than four seasons,with the addition of an annual silent season.But while nature's seasons happen quite naturally,the silent season requires a lot of planning.Ian Wisniewski explains why.
By Ian Wisniewski
It’s called the silent season but that’s the wrong name for it, as it’s a very busy season.“Silent just means that you’re not producing spirit,”says Alan Winchester of Chivas Brothers.In fact, there’s plenty of alternative activity, as the silent season allows for various inspections,maintenance and repairs.The distilling season traditionally ran from around October-May, with June-September the silent season.This followed the agricultural cycle, with the labour force moving to farmwork and cutting peat (some were also laid off as seasonal employees).A seasonal fluctuation of water, with less available during the summer, was another factor.The silent season started to shorten after World War Two, as production levels increased.However, with Scotch whisky’s varying fortunes meant that production levels, and the length of the silent season,were revised accordingly.The current silent season generally lasts about three weeks, if no major repairs are required, otherwise it’s usually four to five weeks from the middle or end of June to mid-August (more recently the Christmas break, and in some instances Easter, is an additional mini silent season).With the summer silent season being the principal opportunity, it’s imperative to maximise on this. And that means preparing the ‘to do’ list, way ahead.“We do on-going maintenance planning during the year,and everything is programmed in advance,”says Alan Winchester.While distillery staff are encouraged to take their holiday during the silent season, there are notable exceptions.After all, a key member of staff must remain available.“I’mprobably busier in the silent season than throughout the year, though with different responsibilities, as most of my time is taken up with contractors. Last year we had 34 contractors on site from seven different companies doing five different projects at one time.You’ve got to watch and co-ordinate,some companies are working together, some are not,”says Highland Park’s Russell Anderson.With distilleries scheduling their silent season around the same time, it’s a very demanding period for the specialists brought in to conduct inspections and undertake repairs.One company in great demand during the silent season is Forsyths, based in Rothes, an ideal location considering that around 50 distilleries are within a 30 mile radius.“During the silent season we literally work seven days a week,12 hours a day, for about two and a half months, it’s very intense.Our biggest problem is that we have highly skilled employees, tradesmen and engineers, which can’t just be picked up.But we can take on labourers for manual duties.Generally we do pretty much everything except servicing mills, which is very specialised,and we have a sizeable electrical division to check out pumps, motors, etc,”says Richard Forsyth of Forsyths.And just as distilleries need to pre-plan the work schedule, specialist contractors such as Forsyths need to have everything in stock, which means pre-ordering items with a longer lead time.“For replacement parts,we have several orders on our books up to eight months in advance,” says Richard Forsyth.Another practical factor is access, which can lead to a sequence of other considerations.“Generally access is quite good to still houses, though we may have to take a window out, take the roof off, or even knock a hole in the wall.“Some distilleries have removable windows, some still house roofs have hatches for lifting off, and it’s not too onerous to remove roof sheets,”says Richard Forsyth.Meanwhile, the few distilleries that malt on-site, including Balvenie,Bowmore, Highland Park, Laphroaig and Springbank,have an even longer check list during the silent season.“As soon as the last load of barley has been delivered we begin the process of inspecting and cleaning the barley intake equipment. Following the final transfer of barley to the steeping vessel we inspect the barley storage bins and transfer equipment for damp and any damage, and if required start repairs,”says Springbank’s Stuart Robertson.The silent season also provides an opportunity to install new steeping tanks, as at Highland Park.“Over the past three years we’ve been replacing our original cast iron steeping tanks to stainless steel.We had to really scrub the cast iron, it was a terrible job, stainless steel is a joy to clean,”says Russell Anderson.The malting floors also require a particular kind of attention.“We initially clean the floors with a scrubbing brush and water to remove any culms accumulated during the malting period.Culms are the rootlets of the growing barley corn which become detached during the malting process.Culms tend to stick to the rough patches of the floor, but can’t grip onto the smooth areas,” says Stuart Robertson.Milling is the usual starting point in the production process at most distilleries, with malt mills serviced by specialist companies, which usually takes two to three days.“It depends if the rollers need to come out and be re-ground. If so, they’ll have new rollers ready to replace them, and they can bring the re-ground rollers back next year,”says Alan Winchester.As a mash tun includes various mechanical elements, these need to be checked thoroughly by specialist contractors.“They’ll do a pre-inspection and plan it in for the silent season.We check gear boxes for any wear, the motors, and the plates at the bottom of the mash tun,”adds Alan Winchester.Meanwhile,wooden washbacks are checked for any repairs required, such as re-hooping or hoops that need tightening, with certain practicalities also required during this time.“As the washbacks are emptied we clean, sterilise and fill them with water.The washbacks are drained and refilled at regular intervals to help keep the water fresh and the wood sound, otherwise they would contract and leak when we restart production.There have been instances of wooden washbacks drying out and falling to bits having been left to dry out for extended periods of time,”says Stuart Robertson.A legal requirement is that stills and boilers are tested by external inspectors, for insurance purposes.“The boiler gets stripped apart and cleaned, which takes about a week.Because it works at a high pressure you need to check the integrity of the welding, and also the build up of scale, as it can get dangerous Apart from a routine annual check, the boiler needs a major survey every five years,” says Derek Sinclair of Inver House Distillers.One way of staying up to date with the condition of the stills is to keep measuring the thickness of the copper, which gradually reduces over time.“We measure the thickness of the copper using an ultrasonic machine. I keep an annual record and by monitoring this over the years you know when it’s going to need replacing and can plan ahead.The wash stills tend to wear out more quickly, around the shoulders where it’s boiling.You can check the thickness of the lye pipe in the same way as the stills, and monitor how the thickness is reducing,”adds Derek Sinclair.Apart from any repairs being required, testing the stills is not necessarily time consuming.“Stills can be cleaned and tested within a few hours. If there is any welding work involved we remove the feints from the last distillation run, ready for the first distillation run after the silent season.“We put the feints into oak vats for convenience of storage, these are inactive oak casks, as we must keep feints isolated from any hot work, otherwise there’s a risk of an explosion,”says Alan Winchester.As condensers, either the more traditional worms, or the more modern shell and tube option,do the same job in a different way, the parameters for maintenance vary.“With a shell and tube condenser it’s the tubes nearest the lye pipe that start to go, where the hot vapours come off from the still and the level of erosion is greatest, and you replace the condenser as a unit,”says Derek Sinclair.Chris Anderson of Dewar’s adds, “We definitely have to look at Craigellachie’s worms every year, even though they were replaced last year.Repairing worms is a big expenditure as they’re prone to wear.A worm is not as thick as a copper tube in a condenser, so it wears, especially at the bends which are particularly vulnerable.” The wormtub also requires various checks and safeguards.“The tub is formed of cast iron plates, which wears out.“We drain the worm tubs when we close for Christmas to protect against the frost, otherwise it could crack,”says Chris Anderson.Once all the checks, maintenance and repairs have been concluded, another requirement is completing the paper work and certification.And then, guess what happens after all this is done?“Right after the previous silent season we start planning for the next one with on-going checks,” says Chris Anderson.