The 900-Year-Old Tannery That Softens Leather with Pigeon Dung
In the heart of Fez, Morocco, the Chouara Tannery has operated virtually unchanged since the 11th century. To transform raw animal hides into supple leather, workers soak sheep, goat, and cow skins in stone vats filled with pigeon droppings and water. The ammonia in the pigeon feces acts as a natural softening agent, breaking down stiff proteins in the hide before workers tread on them barefoot and dye them with natural pigments like saffron and poppy.
An Open-Air Workshop in Fes el Bali
Hidden within the dense, labyrinthine streets of Fes el Bali—the historic walled medina of Fez, Morocco—lies the Chouara Tannery. Built along the river that courses through the heart of the old city, this open-air industrial site has functioned continuously for centuries. Chouara is the largest of the traditional tanneries in Fez, instantly recognizable from surrounding rooftops by its sprawling grid of round stone vessels and rectangular wash pits that resemble an enormous watercolor palette.
The architecture of the tannery has changed very little since medieval times. Thick stone walls enclose clusters of sunken earthen and masonry vats, each designated for a specific stage of skin treatment. The air above the complex is thick with the sharp odors of raw animal hides, fermentation, and drying minerals. Surrounding buildings, many with multi-tiered viewing terraces, crowd right up to the edges of the pits, sheltering leather merchants who sell the finished goods produced directly below.
The Lime Vats and the First Stage of Cleansing
The leather-making process begins with raw hides sourced from cattle, sheep, goats, and camels. Before these hides can be worked into functional leather, they must be stripped of flesh, fat, and hair. Workers submerge the raw pelts into a line of white vats containing a mixture of water, quicklime, and salt. In this alkaline bath, the skins soak for several days while the chemical action loosens the hair roots and halts biological decay.
Once the lime bath has softened the follicles, laborers haul the heavy, saturated hides from the pits. Working with curved, two-handled scraping knives, the tanners manually strip the remaining hair and residual fat from each skin over convex wooden beams. This labor-intensive mechanical preparation clears the grain of the hide, leaving behind clean, uniform sheets of raw collagen that are ready for the crucial softening phase.
The Chemistry of Pigeon Droppings
Raw skins stripped by lime are clean but rigid, brittle, and incapable of absorbing dyes evenly. To break down these stiff protein structures, the hides are transferred to a second set of vats filled with a slurry of water and pigeon droppings. Pigeon dung is naturally rich in ammonia, an alkaline compound produced by the breakdown of nitrogenous waste. In these pits, the ammonia acts as a natural bating and macerating agent, relaxing the tight collagen matrix of the skin.
The process requires continuous mechanical agitation to ensure the ammonia penetrates deep into the fibers. Tanners step directly into the waist-deep vats, treading on the submerged skins barefoot for hours at a time. The physical kneading, combined with the enzymatic and chemical action of the dung solution, transforms tough animal skin into pliable, supple leather that can withstand bending and stretching without cracking.
Colors from Nature: The Dyeing Process
After undergoing thorough washing to purge the softening agents, the supple hides are ready to absorb color. The dyeing vats at Chouara are filled with concentrated pigment solutions, historically derived from local plants and minerals. Ground poppy petals produce vivid reds, saffron and turmeric yield deep yellows, henna produces rich orange tones, cedarwood creates warm browns, and indigo provides shades of blue.
Workers repeatedly submerge the skins into the colored vats, kneading them by hand and foot to ensure the dye penetrates completely through the cross-section of the leather rather than coating only the surface. Once fully saturated, the dyed hides are hauled out of the pits and transported to adjacent flat rooftops, surrounding terraces, and nearby hillsides, where they are stretched flat to dry under the Moroccan sun.
Urban Geography and the Flow of the River
The placement of the Chouara Tannery inside Fez was entirely dictated by medieval urban geography and hydraulic engineering. Tanning requires tremendous volumes of running water for washing hides, as well as an outlet for waste runoff. Chouara was deliberately situated along the Oued Fes (and its local branch, the Oued Bou Khrareb), downstream from the residential, commercial, and religious centers of the city.
By placing the noxious tannery pits downstream, the founders of Fez ensured that fresh, unpolluted water first reached the residential quarters, fountains, and great mosques—such as the University of al-Qarawiyyin—for daily domestic use and ritual ablutions. Only after serving these upstream needs did the river water pass through the industrial quarters, where it flushed the heavy mineral, lime, and organic residues away from the historic core.
Preservation of a Living Craft
In 1981, the Medina of Fez was designated a UNESCO World Heritage Site, recognizing its extraordinary state of preservation as one of the most complete medieval Islamic cities in existence. Chouara Tannery forms an essential component of this cultural landscape, celebrated not as an archaeological relic, but as an intact living tradition where craft techniques, guild structures, and manual methods have survived across generations.
The physical strain on the historic infrastructure, however, prompted a major state-led restoration campaign around 2015 and 2016. Engineers and conservationists carefully dismantled and reconstructed the failing stone vats, reinforced the surrounding buildings, and repaired subterranean drainage channels. The restoration prioritized stabilizing the historic fabric while ensuring that the tanners could continue practicing their trade using the exact methods handed down through the centuries.
Key takeaways
•Pigeon droppings contain natural ammonia, which acts as a bating agent to break down stiff collagen fibers and make hides pliable.
•The tannery operates in successive stages: unhairing in lime and salt, softening in dung vats through barefoot treading, and coloring with pigment solutions.
•Chouara is situated downstream along the river network of Fez to prevent toxic runoff from contaminating municipal water used upstream for drinking and worship.
•As part of the Medina of Fez UNESCO World Heritage Site, the complex underwent extensive structural restoration in the 2010s to preserve its continuous medieval operation.