The simple ingredients haven’t changed much since the first grattachecca appeared in Rome more than a century ago: ice and fruity, colored syrups, seemingly not so different from an American snow cone. But today’s grattacheccari, makers of the treat, are divided into two adversarial groups: the purists and the hygienicals.

The purists insist that the ice must be grated by hand from a large block of fresh ice, using a metal device that resembles a carpenter’s hand plane. The hygienicals use a mechanical ice crusher, on demand, so that the ice does not have time to absorb pollutants before being scarfed up.

Alessandro Simoni is a purist. Six generations of his family have been hand-shaving ice for a total of 101 years at Sora Mirella, a kiosk just off Tiber Island in Rome. “It’s an artisanal product,” he explained. “In the best grattachecca, the ice should be like snow.”

Massimo Crescenzi is no newcomer to the world of icy sweets: His Alla Fonte D’Oro kiosk, just off the Garibaldi Bridge, opened in 1913 and is Rome’s oldest. Yet he is a machine man.