Blending & Bottling
The real art of the maître de chai is in blending brandies of different ages and grape varieties and maturity together to create a style of Armagnac which is consistent year after year. This blending process is called coupage and often also involves the addition of distilled water, or 'petites eau', to gradually reduce the strength to bottling strength, which must be a minimum of 40% alc./vol.
Armagnac may include caramel, for colour correction and consistency (as is commonplace with other aged spirits such as whisk(e)y), but additionally, and rather sadly, sugar and boise are also permitted additives. Boise is a dark goo made by boiling wood and reducing the resulting liquid and this is used to give the impression of extended wood aging.
The addition of boise is used by some producers to save on expensive new casks but is no substitute for investment in oak and the gentle but profound effects of good cellar management and lengthy maturation. The best Armagnacs are made only from water, grapes and yeast with their flavours resulting from distillation and oak maturation.
In Cognac the addition of sugar and boise is commonplace, but while most producers come clean about the use of sugar (which must be less than 2% of the total volume) they deny the use of boise. In Armagnac the use of boise and sugar falls broadly into two camps - the more progressive distillers and négociants who frown upon its use and the more traditional who readily admit to using them, saying both are essential to create the style of Armagnac their customers seek.
The addition of boise tends to show itself in an Armagnac by oak and tannins appearing disjointed - something which is highlighted by the addition of water which appears to magnify bitter tannic notes from the boise. The use of sugar tends to go hand-in-hand with the use of boise as the sugar is used to balance the bitter notes of the boise.
I find the use of sugar tends to flatten an Armagnac's flavour, amplifying fudge and toffee notes while smothering delicate fruity and floral notes. However, there are some great Armagnacs made with boise and sugar, and the best proponents make their own boise to a secret recipe and carefully age their sugar blended with distillate for at least a year prior to adding to Armagnac.