Blending Houses are establishments specializing in the finishing, aging, blending, packaging, and sale of beers brewed outside their own premises. The practice of blending wine is commonplace; many Champagne houses blend and finish wines they have bought from others, Scotch blending houses are well respected, and “new make spirit” flows like water between distilleries, but few are familiar with similar traditions in beer. Breweries have always blended beer within their own houses, and it was once common for even large breweries to produce beer that was transported long distances in barrels, later to be bottle conditioned and sold by others. Britain’s porter beer style is said to have grown out of blends put together in pubs out of various beers, the most famous of these being a blend called “three-threads.” Often such blends would contain some fresh beer, some “stale” beer (stale meaning old, and it was not a pejorative term), and perhaps a dash of something else.

In the Payottenland region of Belgium, lambic was once routinely blended by houses that did not actually produce the wort. The vagaries of spontaneous fermentation have always meant that one cask of lambic beer was often quite different from another, even if they had been filled with the same wort. Each oak barrel of lambic represents its own individual ecosystem of microflora. Some barrels may become fruity, others sour, and yet others touched with an acetic tang. A lambic blending house would buy lambic barrels, often from a number of different producers, and blend the lambics in large wooden vats called foeders (or foudres in French), producing a new beer to match the house style and the desires of their customers. Some of these houses specialized in gueuze, which is always a blend of old beer and young fresh beer, gaining complexity from the former and vitality and eventual sparkle from the latter. Others would take things a step further, buying barrels of wort that had barely started their fermentations and then shepherding them through fermentation, years of aging, and finally blending and possible bottling.

In this respect, a lambic blending house was similar to an affineur of cheese, who may buy the cheese mere days after it is made, but then age it out to ripeness and put the house stamp on it. The lambic blender, therefore, was rarely simply a merchant or négociant. The past tense used here is intentional—whereas free-standing lambic blenders once dotted the countryside outside of Brussels, few are left. Hanssens of Dworp was until recently the only pure blending house left in Belgium, turning out fine, sharply bracing beers in traditional and experimental styles. As of 2011, however, things are stirring, and it seems certain that as interest in sour beer styles rises worldwide, more artisans will hear “the call of the blending foeder.”

See also gueuze, lambic, and porter.