Drying

Drying is a race between two speeds. Water leaves the surface by evaporation, and water reaches the surface from the centre by diffusion. The whole craft of the drying space is keeping those two speeds matched. When evaporation wins, the surface dries into a dense rind while the centre stays wet: case-hardening, and the rind then throttles everything behind it, so a piece can feel firm for months while hiding a soft core. When diffusion wins, the surface sits damp, and damp surfaces grow the wrong things.

Humidity is the throttle. At around 70 to 80 per cent relative humidity the surface loses water only slightly faster than the interior can resupply it, which is why traditional cellars and modern chambers both live in that band. Temperature moves both speeds at once but buys its progress with microbial risk, so cured work dries cool, mostly between 10 and 15°C. Air is the gentlest lever and the easiest to overdo. The surface needs moving air, so that the blanket of humid air around each piece is carried away, but a draught dries the windward face into a rind while the sheltered face lags. Air should drift, not blow.

Fat does not dry. The water lives in the lean, so a fatty piece has less water to lose and loses it more slowly through the fat that covers it. Two salami of identical weight but different fatness finish weeks apart, and the fat cap on a whole muscle is a deliberate brake on one face.

Thickness sets the calendar. Water at the centre of a thick piece has further to travel, and drying time grows roughly with the square of the thickness rather than in proportion to it. A culatello is not simply a large lonza; it is a different length of year.

The scale settles all of it. Weight loss is the working stand-in for water activity, and the house floor for an uncooked dry-cured product is 38 per cent of the starting weight. A piece is finished when it has lost its number, and never merely because the calendar says so.