• woods - eg natural or toasted oak, and
• smoothing agents - eg glucose or glycerine syrups.

Glycerine is a naturally occuring organic molecule that is manufactured by all animals. It is a major part of the animal fats known as triglycerides. Almost all animal fats such as lard, beef fat (tallow), mutton fat and other hard fats are triglycerides. These fats are called tri-glycerides because each molecule is made up of one glycerine molecule to which is attached three fatty acid molecules. A mono, or di glyceride fat such as is found in vegetable fats contains either one fatty acid molecule, or two fatty acids respectively.

Glycerine itself is a molecule made of three connected carbon atoms, with an OH or hydroxl group at one end. This makes it an organic alcohol by classification. This also gives glycerine it's other name of glycerol. Either name is valid.

Glycerine is a natural byproduct of the soap making process. When a triglyceride fat is reacted with lye, the fatty acids are broken away from the glycerol molecule. The end product is three molecules of soap and one leftover molecule of glycerine. This glycerine molecule is valuable so it is recovered from the soap and used in many ways.

Pure glycerine is a clear, oily liquid with a very sweet taste. Think of mineral oil that tastes like honey. Another common name for glycerine is "sweet oil". Glycerine is not digestable by the human body. The oily texture, and sugary taste make it valuable as a calorie free food additive. It is used in MANY foods both regular and those intended for diabetics. Glycerine is also used in many industrial products. Undoubtedly the most famous use of glycerine is the explosive nitroglycerine. If a nitrogen atom is attached to each of carbon atoms in the glycerine backbone, then you have the explosive. Another famous use of glycerine is in cosmetics. The "oil" in "Oil of Olay" is glycerine. Many hand lotions use glycerine mixed with mineral oil and a little lanolin. The most well known in America is "Corn Huskers lotion".

Moonshiners in the mountains of the USA called glycerine "Beading oil". A few drops of glycerine added to low proof moonshine would cause the moonshine to form "beads" around the edge of the jar like those created when high proof liquor is shaken. The sweet taste also concealed the harshness of poor quality moonshine. Glycerine is available from most brewing shops as a finishing agent for wines. It is also available at pharmacies for use as a sweetener or in compounding medicines.

Glycerine is a completely safe and 100% natural compound.

Smoothing Agents

Other Tricks

• a tad of orange flavour [essence], and/or
• a bit of sherry (at 1-5% by volume, and Cream Sherry is said to be best), and/or
• a bit of port, and/or
• a smidgeon of bourbon, and/or
• a tiny tiny amount of honey.

For Whiskey:
Raisin extract: cover with 90-96% neutral (preferably from molasses or brown sugar) spirit or a week, then strain. I use more of this in rums than in whiskey but it gives both a taste I can just describe like "authentic".
Palisander extract: (deep brown, almost black precious wood, quite similar to ebony -but more expensive- used in making violin "souls", sometimes in guitar's... (How do you call where you mark the chords with your fingers?) The dark wood strips they sometimes use to decorate this and sometimes other parts as well are mad from this wood) cover with 60-70% alcohol from beer, more than a month is better. I think this is the wood that smells more like vanilla I have ever smelled.
Vanillin: It's the artificial thing but it smells and tastes quite different from the real McCoy and gives complexity to the oaky flavour, from powder, with 60-70% neutral spirit.
Neutral spirit composition for blending: don't use just one type of alcohol (grain, sugar or corn). Using a large part of molasses spirit refined to over 90% gives a lot of complexity. It's a waste, though, not to use it for rum! In a blind testing a thorough whiskey drinker friend of mine chose the one blended mostly with molasses spirit over the one with predominantly grain (rice + malts) spirit in the blend (this guy doesn't drink rum, he actually frowns on it).
Water for blending: the guy I mentioned in the other message, the Johnnie Walker ambassador, told us they don't use distilled water for blending but "purified" spring water. Of course I asked what he meant by "purified" but people were getting annoyed by my frequent interruptions and rapid-fire questioning and the guy answered someone else's question instead. Do use distilled water for diluting rum. It's what everybody around here uses.
Thyme: from 90-96% neutral. Cover for a week some fresh garden (I think it's English) variety then strain. I use several drops only in my 6 gal. little barrels but trying in bottle (700 ml) sizes 3 drops aid a lot in complexity.
Strawberry seed extract: from 90-96% from beer or neutral. I made some extract mostly from the seeds that where left after making some strawberry pulp and straining it with a very fine mesh. Several drops of this help enhance and give complexity to the oaky flavour

For Rum:
Honey: here they use a lot of this! As much as half a liter per 50 gal. cask (in top of the line rums) so don't spare it.
Black pepper corns: as in whiskey they a give a bigger "woody" touch and more complexity. Several drops.
Lemmon grass: some fresh leaves in 90-96% from molasses. Not more than a few drops. Gives a nice citric flavour.
Coriander seeds: cover some dried whole corns in 60-70% neutral. Watch out because it has a lot of orange flavour but it gives richness and complexity, a "tropical" like flavour.

And the ones I usually recommend for rum: cinnamon, cloves and nutmeg. Sorry I can't be more specific and exact on quantities but extract making, in my opinion, isn't too precise a process either. It definitively is the way to go, as you told me first and I more than once recommend people who ask about rum flavouring, because it's the only way to aspire to some degree of repeatability.

And the last recommendation for both liquors is to get yourself a nice collection of small oak barrels in which you can forget your rum or whiskey experiments and let age, because there's really no good substitute to the old regular ageing. Thoroughly aerating your recently spiced spirits helps fix the flavour/aroma and gives you a better idea of what it would taste like when more mature. In the case of artificial oaking, I found it is essential to impart the whole range of it's flavours to oxidize the spirit just after (or preferably during) spicing. I use a beer carbonating stone and an oxygen concentrator for this but I know that an aquarium stone and air pump does the same job, and if you don't have them just splashing the liquor around two containers should do the job.

Caramel for Colour

Blending

Charcoal & Wood Flavouring

Diagram from http://www.worldcooperage.com

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.

Casks

• http://www.1000oaksbarrel.com/oakbarrel.html
• Lehmans Catalog, or
• World Cooperage,or
• http://www.lindsaybks.com has a book "The Cooper and His Trade" for $18.95 US and it is book number 482.
  
  See http://brewery.org/brewery/library/LmbicJL0696.html#Oak for more information about oak casks. Its written regarding using them for brewing Lambic beers, but there's heaps of info that's still pertinent.
  

Kristofer D offers the following advice :

While oak ageing is an historic tradition, wood management is a far more recent discipline. The benefits of oak ageing have long been appreciated, rather than understood, but it’s only since the 1970s /80s that technical knowledge has supplanted anecdotal theories. With the continual advance of analytical techniques revealing the extent of oak’s influence during maturation, the growing focus on malts, as well as longer maturation terms, wood management has become key. The archetypal ‘maturation mandate’ is to reach a balance between the beneficial characteristics gained from the oak, while also retaining and developing the individual ‘distillery character’ embodied in new make spirit. As oak ageing can account for up to 60 to 70% of a malt’s eventual flavour, or around 40% in the case of heavy peating, it’s a variable balancing act. Because different malts have varying ageing potential, longer maturation does not guarantee a finer malt. It’s a case of variations on a theme: yielding different expressions at different ages, as the oak influence intensifies. Moreover, the appeal of a malt may be a case of ‘less is more,’ or ‘more is more’. The ‘right age’ depends on your own palate.

‘Younger whiskies can have great enthusiasm, then after about 10 years you start to get a real mellowing out and balance; for me the balance is complete within 15 to 20 years,’ says Jim McEwan, Bruichladdich’s malt maestro. ‘At 20 years the oak starts to really exert its influence, and at 25 years has a different, really good character, being mellower, rounder, slightly drier, and the heat drops into the chest, not the palate. Between 25 to 30 years the oak, and where the malt is matured, start to play a very important role. Thirty years and onwards there is a huge concentration of oak in the spirit.’

Maturation can be divided into three essential elements. Subtractive maturation, like a ‘rites of passage’ for the ingenu new make spirit, entails the loss of immaturity. Additive maturation sees the oak endowing the spirit with colour, aromas and flavours, while interactive maturation refers to reactions between the spirit and the oak. This is something of a ‘mystical union’ that is not fully understood, yielding an additional range of characteristics that neither the spirit or oak possess individually.

It would be very convenient if subtractive, additive and interactive maturation followed each other in an ordered, chronological sequence. However, these separate elements effectively occur simultaneously throughout maturation, albeit at differing rates.

Oak-derived flavours, for example, can be evident within the spirit from around six months, though losing immaturity may take a couple of years, or even extend over several. Similarly, filling a barrel with spirit can be said to initiate a form of interactive maturation. This reflects the fact that 2 to 3% of the new make spirit is ‘drunk in’ by the staves, possibly even within 48 hours, and subsequently begins to mingle with the ‘wood extractive liquid’ of the cask’s previous contents (although the full effect will, of course, take years to complete). In fact, specific flavours can be attributed to interactive maturation, due for example to the formation of esters.

‘While The Macallan’s citrus and floral notes originate from the new make spirit, the dried fruit notes derive from esters that have been created during interaction with the cask, and also from oxidisation,’ says David Robertson, The Macallan’s Master Distiller. An initial consideration is the difference between using bourbon barrels, fashioned from American oak, and sherry casks, which are usually produced from European oak, though American oak casks can also be seen in action at sherry bodegas.

European oak, typically harvested from 60 to 150-year-old trees, comprises a looser, more open and porous grain than American oak. This enables the spirit to penetrate the oak more readily than American oak, usually harvested from 40 to 100-year-old trees, which comprises a straighter, tighter grain. The level of tannins, promoting astringency, balance and structure, is also far higher in European oak than in American oak. However, charring bourbon barrels on the inside, while sherry casks are merely toasted, makes the interior of a bourbon barrel more accessible to the spirit.

These technical differences also promote a varying range of characteristics. In terms of colour co-ordination, sherry casks lend an orangey, amber hue, which is distinct from the lighter, golden, straw tint of bourbon barrels. The flavour profile also varies significantly with sherry casks contributing rich fruit (such as raisins, prunes, dates, figs, apricots), fruitcake, fortified wine, almond and walnut notes, spices such as nutmeg, ginger and cloves, not to mention creme caramel, chocolate, and a (positive) sulphurous note, delivered within a rich sweetness.

Bourbon barrels lend a lighter, drier sweetness, with a palate thriving on a medley of flavours: vanilla, honey, various fruits, almonds, hazelnuts, coconut, creme brulee, sherbet, spices such as cinnamon, as well as mint and eucalyptus notes.

The influence of bourbon barrels can be further sub-divided according to the degree of charring. The scale ranges from one to four, beginning with a ‘burnt toast’ effect, and culminating in an ‘alligator char,’ the popular term for a number four, as the surface resembles alligator hide. Various malt distilleries have an inventory of bourbon barrels with a range of char levels, with a heavier char typically giving greater amounts of vanilla, creme caramel, toastiness and hint of smoke, not to mention more intense colour. Alternatively, a milder char promotes greater sweetness, honey and vanilla, while also endowing the spirit with more body.

The ‘fill’ (referring to the number of times the cask has been filled with spirit) is another important consideration, with many distillers using a ‘recipe’ of different fills to help achieve consistency, or a particular flavour profile. Each fill of a cask results in its degree of influence on the spirit diminishing, until the Master Distiller deems it to be exhausted. If a first-fill cask is said to contribute 100% of its available characteristics, a second-fill will contribute around 60%, with a third-fill (when relevant) dropping to around 35%. Consequently, a second- and third-fill require a longer time-frame than a first-fill to complete subtractive maturation. For example, spirit maturing in a second- or third-fill could require about 10 and 15 years respectively, in order to reach the same degree of maturity as a spirit aged for seven to eight years in a first-fill cask.

However, this does not mean that each successive fill also delivers the same flavour profile, in a progressively milder format. It’s actually a case of obtaining varying, rather than subtler flavours from different fills. Then again, it’s also a case of imparting an ‘appropriate’ influence to the particular house style of the spirit. A lighter, unpeated malt, for example, may principally be aged in second-fill sherry casks, to ensure that the oak influence doesn’t predominate.

‘The first-fill of Spanish oak sherry casks gives a dark mahogany whisky, with rich, woody spices such as cloves and ginger, toffee sweetness and dried fruits,’ says David Robertson. ‘When refilled there is a less robust oak influence and more new-make spirity character coming through, together with more apples, esters and floral notes, while the tannins manifest themselves as light spices (such as cinnamon) rather than oak.’

Similarly, a first-fill bourbon barrel offers a different influence to products further down the line. ‘A first-fill bourbon barrel has more natural sweetness and body, the second-fill allows more products of oxidation to shine through and gives more of a floral top note, though greater oxidation also reflects the damper ageing conditions of a traditional warehouse,’ says Dr Bill Lumsden, Glenmorangie’s Head of Distilleries and Maturation.

Spirit within a first-fill bourbon barrel also has optimum contact with the charred layer, though the char’s active influence does diminish during maturation, not to mention physically breaking down within the cask. (Consequently, when the spirit is emptied after the first-fill, some charcoal also leaves the barrel, reducing the level of char available during the second-fill, which is also less active anyway). This gives a lower level of vanilla and ‘burnt heather’ notes which stem from the char, while simultaneously increasing the level of oak influence. Another principal difference between successive fills is the level of wood extractive liquid remaining within the staves of the cask. Not simply a case of residue bourbon or sherry, this liquid also incorporates additional wood-derived compounds, which could total around 75 cl in a 200-litre bourbon barrel, or 10 litres in a 500-litre sherry butt.

The largest amount of wood extractive liquid is present within a first-fill, and released during the first few years, with some wood extractive liquid remaining in the second, but only a minimal amount is released from a third-fill. Traditionally this residue was considered an important element, though the nature of the oak, European or American, is now established as the primary influence during maturation, and the wood extractive liquid a supplementary influence.

Jack Daniels Whisky

Johnnie Walker Whisky

Bourbon

• Soak 2.25 litres 40% in 1 bag of JD's chips and 50 mls of flavour from Classic American Bourbon Sachet and age for 3 weeks
• Soak spent JD' chips ( from above) in 1.125 litres of 40 % and flavour with 15ml of Sprits Unlimited premium bourbon mix Allow this to soak for 3 weeks
• Soak 1.125 litres of 40% in 1 heaped Tablespoon of virgin oak sawdust, add 1/2 a sachet of Classic Tennessee Flavouring and allow to soak for 3 weeks
• Combine in the same ratio
  • 2 x 1125mls on chips and American Bourbon
  • 1 x 1125mls on spent chips and premium bourbon
  • 1 x 1125mls on oak and Tennessee flavouring
• Age for another 4 weeks
  
  I find the best thing is to put down a couple of litres a week. Once the ball is rolling you will have a steady supply of quality Bourbon.
  
  By the way, this recipe took 18 months of weekly brewing flavouring and tasting to perfect. Call it a labour of love.
  
  Allowing for a clean starting spirit this will give you a Bourbon that is best served on its own with just a dash of water to bring out the flavour.

Rum