Olla de barro

The olla de barro is the clay-pot still: a thick-walled fired-clay vessel set into a wood-fired pit oven, with a wooden or copper condensing apparatus on top. Historically the condenser was an inverted clay or copper bowl, with the cooled condensate dripping back through a small wooden trough or carrizo cane into a collection vessel. The architecture is the ancestral pre-Columbian still type in much of Oaxaca and parts of Guerrero, and it remains in production use today.

Three characteristics distinguish a clay-pot distillate. First, the clay walls exchange minerals and trace earthy compounds with the wash during the run, contributing a distinct character that copper does not give. Second, the heat profile is gentler and more variable than a copper still on a steam jacket, which encourages slow extraction of heavy aromatic compounds. Third, clay does not perform the sulfur-stripping chemistry that copper does, so the maestro must manage sulfur compounds at the fermentation stage and during the cuts rather than relying on the still to clean them up. Under NOM-070-SCFI-2016A regulatory-standard NOM is a federal Mexican product norm. Unlike facility NOMs (4-digit identifiers of specific distilleries), a standard NOM defines the rules for an entire category of product: which raw materials are permitted, where the product may be made, how it must be processed, and how the bottle must be labeled. Standard NOMs are written as "NOM-XXX-SCFI-YYYY" where XXX is the standard number and YYYY is the year. NOM-070-SCFI-2016 (Mezcal). The official Mexican standard for mezcal production. Defines three production tiers (Mezcal Industrial, Mezcal Artesanal, Mezcal Ancestral) with specific equipment and method requirements for each, lists the permitted agave species and states, and governs labeling. Enforced by the Consejo Regulador del Mezcal (CRM)., the olla de barro is the only still architecture permitted for the Mezcal Ancestral class, the most restrictive of the three production tiers. The full architectural comparison with the alambique sits in the distillation chapter, and the regulatory consequences for the Ancestral class are walked in the regulation chapter.