Previously to bending and carving, staves are drying, or seasoning. The minimum amount of moisture they have to lose is about 15%. If it’s less, barrels will eventually dry up and leak. Staves for wine barrels are being seasoned for 2 years or more. They are left in the open air, on platforms, to be under the impact of the environment. It helps to reduce the crudest substances in oak and to soften the aromas. For whiskey barrel staves it doesn’t take so long due to the usage of drying chambers. It seems that this is more beneficial for barrel producers. It’s not much of a rule now, because distillers and winemakers are experimenting with the barrels all the time. Producers of whiskey occasionally want them seasoned the natural way, too. And vice versa, there is a trend to age some sorts of wine in old whiskey barrels.