Olla de barro is a term for the clay pots used to make Ancestral Mezcal. An ‘olla’ is a ceramic jar used for cooking stews or soups that typically have short wide necks, even wider bellies and are left unglazed.
In Mexico, they are built into a base of either earth or brick (so that it can be heated by a fire underneath it). The pots are filled with the fermented agave must, a catch plate is suspended inside and a copper pan is placed onto top of the Olla filled with cold water. Once heated, vapours rise, recondense off the pan and fall back onto the suspended catch plate and towards the collection vessel.
The process and science of distillation is the same as traditional pot stills, but the configuration is completely unique, raw, rustic and today is almost exclusive to the production of Ancestral Mezcal.