The Making of Ices

Glaces teach one true thing: freezing is the recipe. The cream or syrup preparation may be perfectly balanced, but leave it still against the cold wall and you get large crystals; keep it moving while every newly frozen film is scraped back into the mass and it becomes fine, smooth, and homogeneous.

The original method assumed a pure-tin freezer turning on a central pivot, a wooden case, a special pestle, saltpetre in the freezing bath, and enough hands to tend the apparatus without pause. The honest home equivalent is a 2-quart ice-and-salt freezer whose dasher moves against the canister, doing the work of those opposing fans for one cook. The original salt-to-ice proportion stays. Saltpetre goes because coarse salt alone makes a sufficiently cold brine in modern equipment, and the household freezer takes over the final hardening.

The ornamental mould and brigade-sized packing operation are scaffolding and can go; the ten-minute prechill, close-packed salted ice, constant movement, and second hard freeze are the dish. Keep the churn moving and remove the frozen film as quickly as it forms. That is the step that decides everything.