Foeder N ° 31, a large oak barrel, was built between 1905 and 1908 by the Bodenheim company from Kassel (Germany). He ended up in a Brussels Lambic brewery in 1919 as part of a large batch of material that was sent to Belgium as compensation for “war damage '14 -'18”. The cask served in this old lambic brewery until 1988 and was then sold together with 20 casks to the Boon brewery. In the first years, these casks were used for the ripening of 1-year lambic for Oude Geuze Boon. The casks that supplied the finest Lambic were eventually reserved from 1992 for the production of Geuze Mariage Parfait, including N ° 31. In 2008 the cask was due for a major overhaul and cracks were found on the underside. In the cooper workshop, the cask was partially dismantled in 2009 and 12 staves (the wooden beams that make up the cask) were replaced by new ones. After the overhaul, they combined 2 worlds: the extra aromas added by the new oak and the now 100-year-old microflora in the wall of the barrel gave a particularly fine Lambic every time after 3 years of maturation.