Four Roses is changing the wood around a familiar recipe. Experimental Series No. 003: Chestnut begins with six-year-old OBSK bourbon, then finishes it in chestnut barrels. The release treats the finishing vessel as a variable in its own right, moving beyond the oak choices usually associated with whiskey.

The starting point matters. Four Roses builds its portfolio from two mash bills and five proprietary yeast strains, giving it ten recipes before barrel selection enters the picture. Keeping OBSK at the center gives this experiment a defined foundation, rather than introducing a different base whiskey and a different wood simultaneously.

The project follows the Mizunara release that opened the series and a subsequent honey-cask expression. All three explore finishing, although the broader Experimental Series is intended to extend into other production variables. Chestnut closes the collection’s 2026 releases at 104 proof, or 52% ABV.

Four Roses describes a profile of toasted wood, vanilla, baking spice, fruit and brown sugar. The small-bottle format keeps the focus on a particular experiment, with the uncommon finishing wood applied to a specified six-year-old recipe.

The 375ml bottle costs $55 and will be sold at the Lawrenceburg and Cox’s Creek visitor centers beginning November 20, while supplies last.