The simplest method of adding wood-derived compounds is the use of oak chips, increasingly used in wine maturation but also used for the maturation of many
brandies. Oak chips of various sizes, and having undergone different heat treatments, are now commercially available and are of particular use in compensating for
the low levels of extractives remaining in old casks that may, none the less, be used to provide a `cask-environment'. Alternatively, renewable stacks of oak planks
placed in large steel maturation tanks may be used for the production of brandies.