The bell founder

At a glance

• Foundry: Saint-Loup, near Orléans
• Mould: core, false bell and cope, all of earth
• Alloy: 78% copper, 22% tin at 1,200 °C
• Pour: about forty seconds

The foundry

The book describes a workshop where time seems to have stopped: an old crane black with soot, two wood-fired furnaces, casting pits dug in the earth floor, stores of clay and wood along blackened walls, and a lingering smell of smoke.

"In broad outline," Dominique Bollée explains, "bell founders work the same way as in the Middle Ages."

Building the mould

The mould is built of three superimposed layers of earth. First comes the core, raised on a brick base in eight layers of Beauce earth, clay and horse dung, shaped with the calibre, a template turning on its axis. Then the false bell, the exact shape of the future bell, coated with hot tallow. Finally the cope covers everything.

Ornaments modeled in wax from boxwood matrices are set on the false bell; under the heat, they leave their imprint in the inside of the cope. A wood fire lit inside the core dries the earth at each stage.

The pour

The cope is lifted, the false bell broken, and the cope replaced, leaving a space for the metal. The moulds are buried in the pit under rammed earth so they will not burst. Bronze, 78% copper and 22% tin heated to 1,200 °C, runs through brick channels into the moulds amid flames. In forty seconds it is over.

Tuning

Twenty-four hours later the cope is broken and the bell emerges, still grey. It is cleaned and polished with sandstone and fitted with a mild steel clapper. A bell vibrates across its whole surface: lower octave at the base, upper octave at the top, fifth and third between. The ratio of diameter to thickness sets its pitch, and the founder checks the note with a tuning fork handed down in his family.