Once it has been selected and matured, the wood is then heated. Just as grapes are transformed into wine through skilful alchemy, the effect of heat on wood is a complex collection of physico-chemical transformations affected principally by heating time, temperature and the presence or absence of water and oxygen. Depending on the conditions applied, this step either allows the wood to be dried in order to preserve the very nature of the oak, or complex sensory compounds to be generated.
Each producer has developed their own expertise in heating the wood without burning it in order to arrive at the desired result.
There are infinite variations, from the method of transferring heat (through convection, conduction, radiation or fire) to the temperature increase curves and heating times.
A wide range of sensory notes is also obtained, from vanilla to smoky notes or caramel, toasted or roasted-type notes.
As stated in regulation EC 1506/2006, no product is added before, during or after the manufacture of wood for oenology. The sensory addition provided by the wood is 100% natural and produced by the oak itself.