Tuesday, August 10, 2010

Paris: City of Plaster

Paris is the most civilized city in the world. This French city is built on the human scale: narrow radiating streets guarantee shadows or sun (your choice) to walk in, cafes occupy most corners, and free public self-cleaning toilets are proliferating. Trees are omnipresent, a river runs through the center of town, the yellow-ochre-tinted sandstone buildings bounce back the light. Public transportation is easy and convenient. The people are professional and friendly when approached with a "Bonjour, Madame" or "Bonjour, Monsieur."

Paris also prides itself as a source of civilization, a city of paintings and statues and elegant design. Its museums are also filled with exotic dinosaurs, extinct mammals, engineering marvels, and more. My argument here is that Paris owes much of its artistic and scientific ability to civilize the world to the deposits of gypsum on which it sits.

Gypsum is calcium sulfate dihydrate; when most of the water is driven off, powdered calcium sulfate hemihydrate is formed (the manufactured analog of the mineral bassanite). When water is added, the resulting material (plaster of Paris) can be molded, cast, carved, polished, waxed, and painted.

Oil paintings were created on canvases prepared with gesso, a plaster/glue mixture, then mounted in gilt plaster frames. Plaster completed broken statues (e.g., the second wing of the Nike of Samothrace), and was used to sculpt maquettes and molds for bronze works. (Unlike marble statues, plaster models could be added to and repaired, allowing sculptors to learn from their mistakes.) House paint was mixed with plaster to produce delicate colors, and murals were painted into not-yet-dry plaster walls. Dinosaur bones (and other heavy but delicate artifacts) were brought from distant lands, safe in their jackets of plaster.

But the most important civilizing role plaster has played is in model making and reproduction of three-dimensional items. Every major city park can have its copy of "The Thinker." Broken but scientifically important samples could be completed and mass-produced: e.g., instead of one irreplaceable Neanderthal skull, anthropologists could take measurements from individual copies at their own universities. And in case an original was lost, damaged or destroyed, copies existed to aid in restoration.

Although replaced in many of its functions by other plaster compositions, acrylics, and polymer resins, plaster of Paris was invaluable in spreading scientific and artistic knowledge, especially in the 1800s and 1900s. And Paris, the City of Enlightenment, still sits on the gypsum mines of Montmartre.

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