Traditional methods of separation of cream from milk involved the use of gravity. In this method raw milk was left in a cool room for a certain period of time. This caused the cream to form a layer above the milk which could then be skimmed off, leaving the milk behind. This process was time consuming and could not remove all the cream from the milk. Also, there was a risk of the milk turning sour due to the time required for cream separation.
It was in the mid 18th century that people began to invent devices which made use of centrifugal force for cream separation but none of them were suitable for commercial use because of the limited quantities they produced. A noteworthy invention was that of German engineer, Wilhelm Lefeldt. He even won a patent for his design.
In 1878, Carl Gustaf de Laval, a Swedish engineer and inventor, invented a cream separator which was an improvement over the others. His device too worked on the principle of centrifugal force.
This device used steam to spin the raw milk at a speed of 4000 revolutions per minute. Centrifugal force caused the heavier milk molecules to move towards the periphery of the container while the lighter cream moved towards the centre. Thus allowing almost all the cream to be separated from milk. This invention of Laval revolutionized the dairy industry.