Mud is probably the oldest and most common flooring stock in history. And, despite a rather remarkable written disclaimer delivered to prospective clients by Ed Crocker of Crocker Ltd., nothing will dissuade upscale aficionados of indigenous building materials from wanting the real thing. So, Crocker's company, which specializes in historical architectural conservation in Santa Fe, N.M., provides clients with either hardened samples or soil specimens of various colors and textures from its own stockpiles. Historically, organic additives — including manure, milk, animal blood, and grain flour — have been used to enhance the setting and durability of the tamped mix, but at least some of these have become strangely difficult to specify.

The charm of a mud floor includes guaranteed cracking, an irregular surface, high susceptibility to scrapes and gouging, pockmarks from high-heeled shoes, and the occasional fisherman digging for night crawlers. With a jack-hammer.

Crocker recommends preparing the substrate for a minimum 5-inch-thick finished surface. He cautions against installing moisture barriers and ductwork under the floor, and specifies up to a 12-week setting and drying time. Radiant-heat tubing is generally acceptable under the floor and can even be used to accelerate drying, albeit at lower than final operating temperature.

Once successfully installed and cured — and there's no guarantee here; Crocker has experienced floors that retained a rubbery consistency for months — happy clients can run barefoot over an unusually beautiful and durable surface. The floor is sealed with a sequenced mix of boiled linseed oil and mineral spirits, which produces a deep, rich, low-gloss patina.