Colonial people made butter by hand, using fresh cultured cream. The process involves separating the fat from the cream by means of agitation, which is technically known as "concussion". In colonial times, this was most often done in a wooden churn, which is a tall wooden barrel with a long handle. Using the handle, you must beat the cream in the churn until the fat becomes a solid and separates from the liquid. Although time-consuming, it is not difficult to churn butter. You can buy a colonial-type butter churn from several online sources.
For the best texture and flavor, you must begin by culturing your cream. This is very easy to do, whether using raw cream (as colonial people would have done) or store-bought pasteurized cream. For raw cream, simply place in a bowl and cover with cheesecloth. Let sit in a cool room for at least eight hours, or up to a week for a very strong cultured flavor. If your room temperature is higher than 60 degrees, place cream bowl in a bowl of cool water. If you cannot find raw cream, you can culture store-bought pasteurized cream by adding one tablespoon of buttermilk or sour cream per cup of pasteurized cream, and allow to sit at room temperature for 8 to 12 hours.
Clean your butter churn thoroughly! Scald the inside of the churn and the paddle or handle with boiling water. Allow to cool, and then add the cultured cream, leaving room at the top for the cream to expand during churning.
Begin churning. The butter will go through three phases: it will first begin to look like whipped cream, then will turn yellow and grainy, and finally will break into clumps of butter which have separated from the buttermilk. The process will go more quickly if your churn in a cool spot, about 50 to 60 degrees Fahrenheit. Once the butter has clumped, drain off the buttermilk and place butter in a large bowl.
Holding the bowl at an angle, press the butter against the side of the bowl with a wooden spoon or your fingers to squeeze any remaining buttermilk from the clump. Fold the butter over itself, and repeat the process until you cannot squeeze any more liquid from it. Remove the butter to a plate, drain the liquid from the bowl and dry the bowl. Return butter clump to bowl.
Wash the butter in cool water, again pressing and folding the butter. Drain the water, and wash and press again. Continue this process until the water runs clear. Again remove butter to a plate, and drain and dry the bowl. Return the butter to the bowl and press and fold (without washing, this time) until you cannot squeeze any more liquid from the butter.
Enjoy immediately, or wrap and refrigerate for up to one week.