How It Works: Cream Separator

Cream separators utilized centrifugal force to separate the cream from milk

| May 2012

There were a lot of things I looked at with wonder while growing up on a farm in Kansas. One of the most intriguing was the cream separator. Every morning and evening, my parents poured the produce from 20 cows through the separator, which instantly divided cream from milk. The cream flowed into cans destined for town; the milk went into buckets that were dumped into a hog trough.

By the time I was in high school, though, the cream business had disappeared, along with any use for the cream separator. From that point on, area farmers adapted to the market for whole milk or got out of the dairy business. It’s no surprise, then, that most people today have never seen a cream separator work, let alone know how it works. Simply put, the separator uses centrifugal force.

Putting gravity to work

In its raw form, milk contains a mixture of large and small butterfat particles held in suspension because they weigh less than the other parts of whole milk. It’s not unlike drops of oil mixed with water.

In both cases, lighter material rises to the top when the mixture is left standing. Consequently, when whole milk sits for some time, the heavier skim milk gradually settles to the bottom of the container, while the lighter butterfat rises to the top.

The earliest methods of cream separation involved gravity. In one early method, milk was poured into shallow pans (2 to 4 inches deep) known as setting pans. The pans were placed in a cool, clean room for 36 hours, allowing the cream to rise to the top. At that point, it was skimmed by hand with a tool called a cream skimmer.

This method made it difficult to handle large amounts of milk. As much as 30 percent of the cream was left behind. What’s more, if the milk wasn’t properly stored, the cream could easily sour.