Prior to the mechanization of its production process, butter was churned by hand. After churning, which separated the fat (butter) from the liquid (buttermilk), the last of the buttermilk needed to be removed so that the butter would not spoil so quickly. This lever butter worker was used in this process. It was also used to work salt into the butter.

 

The tool, which is missing its triangular-shaped tray, was patented in 1877 by Oscar S. Cornish and David W. Curtis of Fort Atkinson, Wisconsin. Freshly churned butter was placed in the tray and the lever was rolled back and forth over it to work out the buttermilk. The liquid drained out of the narrow end of the tilted tray into a container below. The tray had an iron fastened across the narrow opening into which one would place the end of the lever.