⚙️ Butter churn

A butter churn is a device in which cream is churned into butter. Long, hard mixing tears the thin skins around the fat globules. The fat clumps together into butter grains, and liquid buttermilk is left behind.

There are many kinds of butter churns. The best-known old one is a tall wooden tub with a plunger: a stick is moved up and down through a hole in the lid. There are paddle churns with a handle and barrel churns: a barrel lying on its side is turned with a crank, and the cream sloshes about inside. Barrel churns were a European novelty of the 18th century. There was even a churn built into a rocking chair. Nomadic peoples made butter by shaking milk in leather bags, sometimes tying the bag to an animal.

The oldest known vessels for churning butter are made of clay. Archaeologists found them in the Middle East, and they date from the Copper Age. Modern dairies have large churns holding 8,000–14,000 litres. But these are more and more often replaced by continuous butter makers: they turn out from 200 to 10,000 kg of butter an hour.