The 1965 frantoio

When we restored the press in 2023, two things were obvious: it would never be as efficient as a modern hammer-mill, and it would always make better oil.

A frantoio is a stone press. Two granite wheels, each about a metre across, rotate around a central spindle on a granite base. The olives — fruit, pit, skin — are crushed under the weight of the stones for 25–35 minutes. The resulting paste is then spread onto woven mats, stacked, and pressed hydraulically to release the oil.

Total cycle time: about three hours per batch. A modern hammer-mill does the same volume in 35 minutes.

Why bother?

Heat. Hammer-mills generate friction; the paste comes out at 30–34°C even with cooling. Stone-mills work cold — under 25°C even on a warm October day. Above 27°C, the polyphenols start to oxidise; the bitter, peppery compounds soften and the shelf life shortens.

Air. Hammer-mills emulsify. The paste comes out aerated, oxygen-rich, ready to oxidise on contact with light. Stone-mills don't aerate — the paste is heavy, almost like dough, and the oil released from it has had less air contact.

The trade-off is yield. We get about 14 litres of oil per 100kg of fruit. A hammer-mill would get 16–18. We're fine with that.

The eight photos in this post — a Stefano-the-Tuscan-miller demo from October 2024, the wheels mid-cycle, the paste on mats, oil flowing into the steel tank — are below.