Abstract: A cap adapted to cover an end of a cask for maturation of a spirit, comprises a body having an outer plate and a flange extending from the outer plate, and an inner plate spaced from the outer plate. The inner plate lies between the outer plate and the end of the cask when the cap is in place on the end of the cask. A layered or ridged spacer can separate the plates, and can permit fluid transfer in the space between the plates. The inner plate can be resistant to vapor transfer, and can be pressed against the outer surface of the end of the cask when the cap is in place on the end of the cask, and leaves an annular area of the end of the cask uncovered.

Abstract: A cap adapted to cover an end of a cask for maturation of a spirit, comprises a body having an outer plate and a flange extending from the outer plate, and an inner plate spaced from the outer plate. The inner plate lies between the outer plate and the end of the cask when the cap is in place on the end of the cask. A layered or ridged spacer can separate the plates, and can permit fluid transfer in the space between the plates. The inner plate can be resistant to vapour transfer, and can be pressed against the outer surface of the end of the cask when the cap is in place on the end of the cask, and leaves an annular area of the end of the cask uncovered.