Charcoal & Wood Flavouring

It is estimated that around 80% of the flavour of bourbon and whisky comes from the oak barrels used to store them in. We can replicate those flavours by soaking our spirits with oak chips or shavings. Start by using one teaspoon of oak per litre of alcohol, and let it soak for a week. Taste test frequently to find the level of flavour intensity that suits you - eg maybe a little more oak, or longer, or different % alcohol, or different levels of oak toasting.

Geoff writes ...
Maybe consider the size and shape of the barrels that are used to age the spirits you are trying to emulate. Calculate the ratio of the inner surface area to the volume of the barrel. Based on some whisky barrels I've seen, I add about 70 square centimetres of oak per litre of 55% spirit. Keep in mind that one "strip" of oak has two surfaces that interact with the spirit. I age spirits in 4 litre glass bottles and add thin strips (<1mm) of oak that I had wrapped in aluminum foil and lightly charred on the stovetop. So if my oak strips are 2 cm wide I cut a total length of 70 cm, but I usually break such a strip into a few pieces before charring and adding them to the jug. Gives nice colours and flavours and generally a smoother drink.

For an excellent article on the composition of Oak, and its affect on maturation, download oak.pdf (690kB) which was from the Cooperage website

Donald advises ...
Oaking - Several different flavors can come from a single type of oak if alcohol strength is adjusted during maturation. 55%-53% will give vanillins, 40%-50% will give a mix of vanillins and sugars, 40%-49% will give sugars.

What I like to do is start at 55%-53% for first phase (1 to 12 months) then dilute to 40% (3- 12 months). In this manner I am adding sugar from the cells of the wood while I marry the dilution water to the whiskey. This results in rich vanilla oak charater with silky legs that cling to the side of the glass. The procedure works well with all types (chips or BBL) and varieties of Oak.

If you can't buy the commercial toasted/natural oak chips for flavouring and aging, you can try making your own. Make sure you use oak or non-resinous wood - using a soft resinous pine will only give you a retsina. Be ingenious when looking for old oak - locals here use bits of old furnature etc (after shaving off the varnishes etc). Smoked manuka timber is particularly good.

To make your own toasted timber, find a tin with a push on lid of 1-2L. Split your timber into thin enough strips to fit your bottles. Light the pieces, and when well charred, place in the tin. Place the lid on lightly to snuff out the flames. Add more wood as it becomes ready, replacing the lid each time. When cooled, push the lid on tightly to retain the smokey aroma until ready to use.

Another way is to wrap the oak chips/shavings in aluminium foil, and bake them in your oven for a while.

The temperature of the toasting will affect the flavour that develops...

Diagram from

Hexenwolfe writes ..
    Jack Daniels is 140 proof grain whiskey when it goes into the barrel. The barrel is made from American white oak from Missouri. Each barrel is roasted at 450 degrees for four hours then flash charred over a 1500 degree gas flame for 4 minutes. It is then steam quenched to "activate" the carbon (and put out the fire!). The roasting carmelizes the sugar in the wood before the flash burn creates the charcoal. The steam treatment not only puts out the fire, but it causes the charcoal to expand like popcorn creating trillions of tiny bubbles. This GREATLY expands the surface area of the carbon. A fresh barrel will have approximately 1/3 inch of char on the inner surface.

    Jack Daniels Whiskey is aged in the barrel for four years. During this time the barrels are racked in wooden barns. There is no heating or cooling in the barrel houses. The heating and cooling of the natural weather cycle in central Tennessee causes the whiskey to expand and contract with temperature. As the whiskey expands it is forced into the wood.In the wood it dissolves carmelized sugars, and tannins. As it contacts, it moves out of the wood and back into the barrel. The carmelized sugars give the whiskey it's red-brown color. The whiskey will penetrate approximately 3/4 of the thickness of the barrel stave. The penetration line is easy to see on an old barrel stave. Jack Daniels uses each barrel only once. After the whiskey is removed, the barrel is sold to other whiskey makers, European wine makers, the makers of tobasco sauce, and the public.

    After ageing the whiskey is diluted to 80 proof before bottling. To answer your question regarding toasting and charring... They are not the same process. Toasting is baking the wood at 450 to carmelize the sugars. Charring is actually burning the surface of the wood to create charcoal. For hobbiests, it is easier to use toasted chips for flavor, and activated charcoal filtering for clarifying. These two processes are combined into a single stage process in barrel ageing.

Jack advises :
Charcoal that can be used to smooth the flavor of bourbons and rums may be made at home like this: use either hickory, oak, or sugar maple wood (buying it from a lumber supplier is easy enough) as these are proven to be nontoxic.

Split the wood into finger-width sticks about 4 to 6 inches long, then pack them into an old coffee can that has no more of that coffee smell or any rust. Pack them in standing upright so there isn't much space between them. Once the can has a solid layer of these sticks crammed in together like sardines standing upright, cover the top of the can with a layer of heavy tinfoil that has a pencil sized hole in the middle of it. Place this arrangement on your propane burner (this is not to be done inside!!), and set the heat on high. After a bit of heating up, some steam, then other various flammable organic gases will evolve off (if the foil swells up, make the hole a bit larger- try not to burn yourself). Once there is no more gas/steam coming out, turn off the heat and let the can sit outside to cool on it's own with a cover to exclude any air from getting in. Once cool, rinse any ash off in some cold water and use however you wish. Do not poke any holes in the coffee can - that will allow air into the mix and turn all of the wood into ashes, instead of turning it into charcoal.

Using a pressure cooker to inject steam could also be attempted to try an make activated carbon, but I haven't tried it.

Jack also writes :
I see people trying to duplicate Jack Daniel's Tennessee Whiskey (It is NOT a bourbon - the charcoal filtering procedure was legally recognized as producing a separate type of whiskey after World War II) on some of the e-groups; the essential step is to filter the unaged spirit through charcoal (not activated carbon) that has been made out of sugar maple wood
(see How to Make Charcoal at Home by Dan Gill).

The residual sugars in the charcoal give a slight sweetness to the finished spirit, and the limited absorbing ability of the charcoal only makes the stuff smoother, but doesn't strip all the flavor out. I have tasted homemade whiskey and rum made and filtered in this method, even at "barrel strength" (75%) they were very smooth - no ice was even needed.

For a "Wild Turkey" style flavour, Wal advises ...
No recipe, but here are some quotes that might give a lead:
1) Aging technique. "Wild Turkey is distilled and put into new barrels at a much lower proof than most Bourbons - a costly method that results in less of the flavor being cooked out. The barrels are made of the finest new oak with the heaviest char available, imparting a smoother flavor and a deep amber color."
2) Taste. "best flavors of our premium bourbon, but with real honey to give it sweetness...." "real honey" "obvious notes of vanilla and citrus" (this could come from the heavily charred American oak barrels). "Wild Turkey Liqueur is a sweetened cordial with honey" - 30%abv.
3) Wild Turkey Liqueur was introduced in 1976 - htp:// (possibly it was introduced to compete with honey based Scottish whisky liqueurs).

It appears to me that a starting point would be to age your raw whiskey distillate in heavily charred American oak chips, and then add a pure honey to say 25% sweetness (start with a 250 ml cup/l). Some orange peel might have been added to imitate Southern Comfort(?) The vanilla would probably come from the American oak which has that characteristic.

The "Household Cyclopedia" recommends ...
The flavor of malt spirits is highly improved by putting 3 1/2 oz. (100 g) of finely-powdered charcoal, and 4 1/2 oz. (125 g) of ground rice into a quart (1 L) of spirits, and letting it stand during 15 days, frequently stirring it; then let the liquor be strained, and it will be found of nearly the same flavor as brandy.

You can also use virgin wood shavings - the greater surface area will work faster. Taste regularly to ensure that it doesn't get too wooded, then filter out when ready.

Wood-essence can be made by soaking the shavings or toasted wood in 70% alcohol for a couple of weeks, then strain them off. Another suggestion is to pressure-cook the shavings with neutral spirit for 10 minutes at medium pressure, but this sounds risky!).

Brian writes ...
Oak chips in Australian home brew shops anyway are usually Quercus Alba (American White Oak) and are applied as per the label. I prefer to use a natural essence as not only is it more accurate, but is actually "less harsh". To make this infusion yourself, take equal proportions (by volume) of chips and neutral spirit at about 70% and soak for approximately one month, agitating as often as possible or percolate using a pump, then separate the two and apply solution (tincture) at a rate of about 10/15 ml per litre, or to taste of spirit at 40%. Or if you want to be really upmarket, take the tincture and simmer it very slowly until the volume is 75% less than original and you should have a fairly concentrated essence. In processing, remember it's frightfully volatile!!!

Jeanette suggests to use the toasted oak by ...
I am writing to tell you of my way of aging bourbon ( or whisky for that matter ) We are doing this one bottle at a time.
  1. Line up bottles to be used, add your undiluted spirit, and put in appropriate amount of flavouring. Personally, if it says 10ml per litre, I add 15ml.
  2. In a stainless steel saucepan, put in amount of water needed to top up one bottle only. Add one tablespoon of toasted oak chips.
  3. Bring to boil, then immediatly turn heat down and simmer. We don't want to boil off all the aromatics of the oak. At this stage add a large teaspoon of glucose and stir in well.
  4. Simmer for about 5 minutes, bring to boil again, then take off heat and let cool. The mixture should be a lovely brown colour.
  5. Strain and add cooled mixture to your bottle of spirit and it is ready to drink. Or don't strain, and keep the flavour coming for an even smoother, flavourful drop in the future.
Compare the aroma of your liquor to the conventional, and long way of aging.

From Cheryl (Victoria, Canada)...(posted on Distillers newsgroup)
The way I make my whiskey is a cup of virgin (untoasted, french oak) oak to 1 gallon of vodka, and it sits for a month and gets filtered and is ready to drink. I have made a scotch tasting whiskey using the same method, only with toasted oak.
to which Ray Toms added ..
I find that you can overdo the toasted oak but not the plain oak. I restrict my toasted oak to one teaspoon for short term oak aging and double it to two teaspoons for long term (in excess of 12 months) aging whereas I use 3 teaspoons of plain oak for short term aging and 6 teaspoons for long term aging. Excessive use of toasted oak can leave a burnt flavour in the whisky.

See below about using casks

Where to source the wood chips ? Donald suggests ...
Whiskey barrel chips can be obtained by routing the inside a used whiskey barrel. Good results also come from wine barrels (sherry & port if possible). There used to be companies (20 years ago) that would convert whiskey barrels to wine barrels by shaving the charred wood layers out to toasted wood. They would just give the chips away. FYI - red oak has good flavor too, it just needs to be used in chip forms because red oak barrels leak.

Wal writes ...
its worthwhile to extract notes from University of Nevada, Tourism course 'FAB 362 Distilled Spirits and Liqueurs': (of which I have a local copy : FAB 362 because their link is no longer working)

The changes in the spirit during wood aging are caused by 3 types of reactions occuring simultaneously and continuously in the barrel.
1)complex wood constituents are extracted by the liquid
2)there is oxidation of components originally present in the liquid as well as of material extracted from the wood
3)there are reactions between various organic substances present in the liquid, leading to the formation of more and new congeners

As with wine, the type of wood is very important and most of the major spirits have strict requirements. Bourbon whiskey regulations require that the barrels be new, and that the insides be charred. This is done by setting the inside of the barrel on fire until a layer of char is developed. Most other whiskies and other spirits do not have to be aged in new, unused wood, nor do the barrels have to be charred. Charring improves and softens the taste of the spirit and provides both body and color.

The manufacturer will decide what specific type of spirit to make and there is a close relationship between distilling and aging strategies.
Anything distilled over 95%abv is legally termed "neutral" spirits.
Bourbon cannot be distilled over 80%abv
Cognac cannot be distilled over 72%abv
Rum is distilled at 85-96%abv
Scotch malt whiskey is distilled at 70-71%abv
Canadian whisky is distilled at 70-90%abv

The congeners, those secondary products produced during alcoholic fermentation, consist of acids, esters, aldehydes, fusel oils, extracts of mineral salts and solids in minute quantities. Collectively, they do not amount to much from a percentage standpoint, but they are determining factors as regards product character.

Esters are volatile substances which give aroma to the spirits Aldehydes are produced from alcohol/air reactions and contribute to the character of the spirit.
Fusel oils are higher alcohols and form complex mixtures. Not all these compounds are desirable, and even those which are, should be present in specific amounts.

The use of copper stills is important because the contact between copper and liquid traps fatty acids and sulphur elements. Cognac regulations permit French oak only. The barrels are not charred. Freshly distilled cognac is placed in new barrels perhaps for 16-18 months. Barrels are considered new the first 3 times they are used. The first of the 3 will be for only a few months since the wood will impart excessive tannin to the spirit. The second use may be for up to 2 years and the third even longer. The barrels are kept filled unlike bourbon and malt scotch whisky. Blending is a key factor. Both caramel and sugar syrup are legal and regulated additives. An unregulated practice is the use of oak chips soaked in old cognac and left in cask for months or years. The purists regard that the character from this is rather hard and tannic.

Bourbon whiskey
Charred barrel aging is said to impart the characteristic vanilla and caramel flavor of Bourbon. There are 4 grades of char and each distiller has their preference. Charring produces a layer of partially caramelised sugars below the char. Charring imparts color to the spirit and whiskey stored in new, charred white oak develops the distinctive red-amber color. Additives are not permitted. The used barrels are sold to distilleries in Ireland and Scotland.

Scotch malt whisky and Irish whiskey
Most malt whisky is matured in Bourbon barrels, only 4% is in sherry barrels. One difference between American oak and Spanish oak is that the American species is harder and consequently matures whisky more slowly. Spanish oak contains more resin which effects the flavor. Sherry and bourbon leach out the stronger tannins and oak extracts, creating a lighter product.

Maturing is done is used in previously used barrels which may or may not have been charred. Puerto Rican law requires a minimum of 1 year in wood. Fuller and more distinctive rums result from increased wood aging of a minimum of 3 years. Caramel is used to adjust the color. The typical dark color of Jamaican rums is due to the caramel added. The coloring is produced by heating sugar solutuins to about 82C (180F) to evaporate the water and caramelize the sugars.

Wal then asks ...
Could the homedistiller make a convenient oak essence? In France flavoring/maturation shortcuts are practiced that homedistillers can copy. In France, four additives are allowed for cognac and armagnac. See: (Dead Link ?)
  1. Water
    To cut excessive alcohol. But vintage cognacs/armagnacs achieve their 40%abv by slow evaporation (3% a year), so dilution has an effect on flavor and for traditionalists reduction is a bad word. For homedistillers a lower %abv distillation will contain more flavor compounds.
  2. Boise (e is accented)
    A boise essence is made by boiling chips in water and then removing the chips and slowly reducing the remaining liquid. What one is left with is a dark brown liquid that is replete with wood flavor and tannin. Another source mentions infusing shavings in cognac. Charred French oak chips are also available which act like charred white Ameican oak chips - more caramelised sugars and vanillin i.e. softer flavors.
  3. Sugar Syrup
    Used to add sweetness. Normally added if a cognac/armagnac is too tannic, or to remove any rough edges. It is viscous, and can either be dark or light. Legally 2% can be sugar syrup. 1 tsp/1 litre(quart) is a good starting point.
  4. Caramel
    A liquid from burnt sugar. It is dark in color and slightly bitter in taste. It is used to adjust color and establish consistency or give the spirit the impression of being older and therefore smoother.
Ideas for discussion:

American whiskey can gets flavors only from the charring of American white oak staves. American white oak contains less tannins and more vanillin than French oak. Filtering through maple charcoal is also practiced, and this has an effect on flavor due to caramelised sugars in the maple charcoal. A Bourbon essence could possibly be made by soaking charred American oak chips in Bourbon.

Rum is aged generally in used Bourbon barrels. Reusing the chips from making a Bourbon essence and soaking in aged rum (in effect diluting the wood character) would emulate a used Bourbon barrel.

Scotch and Irish whiskies are aged by reusing Bourbon or Spanish sherry barrels. Irish whisky is usually triple distilled (90%abv) as opposed to the double distilled peated malt Scotch whisky. So the amount of distilled congeners is different in the two styles. An essence could be made by soaking in aged whisky for a second time, American oak chips that were soaked previously in Bourbon, or European oak chips previously soaked in Spanish dry oloroso sherry.

The use of sugar and caramel is practiced in all the above liquors except Bourbon and Tennessee whiskies, and a starting quantity to achieve smoothness would be 1 tsp/litre. The amount of caramel (burnt sugar) used would depend on the style required.     This page last modified Tue, 20 Jan 2015 20:51:05 -0800