British Science Advises Charred Barrels for Spirits (1806)

Science vs. Accidental Explanations

One of the great questions in whiskey history: how did new charred barrel emerge to age bourbon and straight rye whiskeys? It is a question likely without  definitive answer, but progress can be made, as will appear.

The Filson Historical Society in Louisville, KY announced some years ago that the first mention known of the charred cask for American whiskey is in 1826. (The term bourbon itself, for a type of whiskey, first appears in 1821 in a Maysville, KY newspaper, a fact known since the 1960s at least).


On the Filson’s page, it is explained that a grocer in Lexington requested, of a distiller in Bourbon County, John Corlis, that his whiskey be delivered in barrels charred to 1/16″. The letter was polite, leaving the decision to the supplier, but leaving clear the opinion that the spirit would be “much improved”.

By the end of the 1800s the aging of bourbon and rye in new charred oak was routine, and associated with fine Kentucky and Pennsylvania whiskey. At a minimum though, one can infer that around 1825 some whiskey was aged in charred barrels (new or other) and prized as such, at least in Bourbon County, by then much reduced in size from its original area that took up much of northern Kentucky.

This doesn’t mean, in other words, that all Kentucky whiskey was aged in a charred or other barrel c.1825. Henry G. Crowgey, in his landmark study Kentucky Bourbon: The Early Years of Whiskeymaking, makes clear that in the first quarter of the 1800s, whiskey is described without reference to its colour. Sometimes, he said, it was called “old” and finally by reference to a term of years: 1, 2, 3 etc. years old.

For example, he cites a whiskey advertised in 1818 as seven years old. But generally at the time much whiskey was sold new, hence white and taking no or little colour from the barrel. Early texts such as Samuel M’Harry’s from 1809, Practical Distiller, also clear again some whiskey was aged in barrel and some was not.

M’Harry, writing in Philadelphia, seemed to like the colour and flavour that wood imparted. He also noted this was undesirable for certain purposes, e.g. when the whiskey was intended to be blended with beer or brandy. This was to increase the strength, or “extend” it in the parlance of the day.

M’Harry writes of using straw to burn the wood vessels used in mashing and distilling whiskey (more than storing it, that is), but he is not clear if they should be charred black. His main concern seemed to be to kill microorganisms which could acetify or otherwize spoil a mash or fermentation; this is not really the same as charring barrels black to hold whiskey for years.

By mid-century though, long aging of Kentucky whiskey in wood became common. Even before the Civil War the red colour of James Crow’s whiskey made at Oscar Pepper Distillery was noted as a virtue. By the end of the 1800s, the aging of bourbon in new charred oak was considered necessary to lend the product its keynote flavour and e.g., the fine red colour of Jack Daniel’s whiskey was recorded in this period.

Many theories have been put forward for the use of the new charred barrel to age American whiskeys, everything from wood casks being charred accidentally from a fire onsite and used anyway to store whiskey, to charred barrels being a by-product of sanitizing of wood vessels and casks to prevent a soured or musty taste.

Some have suggested too that in heating staves to fashion barrels, which is necessary to make them pliable, some staves were burned accidentally but made into barrels anyway. Filled with whiskey and tasted years later, these barrels were found to have much improved the spirit. All these theories are a form of the accident explanation. The John Corlis explanation seems to be that early merchants who stored and sold whiskey hit on the idea, which IMO is a variant of the accident theory.


As brandy has been barrelled for centuries, this practice may have inspired the same idea for American whiskey, as it no doubt did for the oak storage of Irish and Scotch whisky and rum. From my reading though, Cognac barrels were never charred black like American bourbon barrels. They were and are toasted to varying degrees but not to the point of creating the famous “red layer” of a bourbon barrel, the part just under the char layer which imparts caramelized wood sugars to the whiskey. Still, old French practice may be part of the picture.

As we know from Scotch whisky and rum, fine flavour can result from long aging in uncharred oak wood (or reused charred barrels, whose red layer is considered exhausted). But the keynote flavour is quite different from that of bourbon: generally less sweet and charcoal-like. The peat flavour of some malt whisky is not really the same thing.

Against this background, it is useful to point out that scientists in Europe in the latter half of the 1700s and early 1800s were experimenting with the use of charcoal and charred barrels to improve the taste of various liquids, notably water but also wine and spirits. J.T. Lovitz, a Russian scientist, experimented with charcoal and charred casks to ensure water wouldn’t sour or “putrefy”, as explained in this modern text on water treatment.

The Russian navy adopted this practice with success, as did the British navy somewhat later. The French chemist Claude-Louis Berthollet (1748-1822) considered that wine would not spoil if held in charred barrels and is remembered for his work on charcoal filtration in general.

The suggested  application to alcohol drinks was a derivative of these experiments through the 1700s with charcoal and other materials, e.g., sand, to sanitize in particular water for municipal use. It was seen that charring the barrel creates a thin charcoal layer and it was felt this kept water and other products fresh for longer. Meats too were stored in charred barrels to retard premature spoilage. In 1806, a renowned British scientist and chemist, William Nicholson, advocated a similar system in the Journal of Natural Philosophy, Chemistry and the Arts, Volume 15but he extended it to distilled spirits:

Spirituous liquors likewise [like wine] dissolve the extractive part of wood, and receive qualities which are in some cases valued, but others detrimental. The charred casks would prevent this effect. In a word, the casks which have received this preparation may be used for all purposes in which liquids are to be preserved, without being affected by the extractive part of the wood, and they prevent the putrefaction to which some of them may be subject.

Nicholson earlier cites in his work the researches of Berthollet regarding charred barrels to store wine, and refers to the beneficial effect of charcoal on the liquid. The concern was to keep the good parts of wood storage – I would infer tannins and colour –  and exclude the bad parts which lent a fetid or bad taste to water or wine. I think they were driving at controlling wood saps, as these would be burned out by the charring and the charcoal layer would neutralize any residual effect on the liquid. I once tasted beer stored in a new oak barrel and it was virually undrinkable, piney and very off-flavoured.

In the end, the British used ex-sherry and reused American whiskey casks to store whisky, so charring perhaps was viewed as less significant than Nicholson thought, although it is interesting that 99% of the barrels the Scots, and the Canadians, use are charred, except re-used. But the point is, we have a scientist in a British journal advocating holding spirits in charred wood, and 20 years later, there is evidence charred barrels were being used to store Kentucky whiskey with the implication that for some years at least the practice had been ususal.

The British founded the main American settlements. British books in the sciences and other branches of knowledge circulated in the country. Americans were up on the latest developments in distillation as we know from their early adoption of steam distillation.

In my view, the American adoption of the new charred barrel may well have been inspired by these European developments – the 1700s ones referred to on charcoal filtration for water, the use of charred barrels to store water and wine on voyages, and finally specfic advice in 1806 to store spirits in charred barrels to prevent off-tastes and deterioration.

Is it possible Kentucky grocers or merchants hit on the idea independently? Certainly, but I regard the European background as too much coincidence: the knowledge likely had penetrated to America’s interior so that Kentucky distillers and indeed merchants applied it methodically, not by accident.

Note re images: the images above were sourced from the entries on “bourbon whiskey” and “William Nicholson” in Wikipedia, here and here. They are believed available for educational and historical purposes. All feedback welcomed.