How to Make Butter Without a Separator, Without a Churn, and Without Difficulty
Start by pouring one gallon of milk (fresh from the cow) into a clean container. Chill the milk quickly and keep it in the refrigerator for at least 12 hours. Then skim the cream off the top of the fluid with a spoon. When you begin to see watery skim milk in the spoon, stop skimming.
Next pour the cream into a jar, cap the container tightly, and let it sit on the kitchen drainboard for approximately 12 hours (or until the cream is about 75 degrees Fahrenheit and smells slightly sour). This is called ripening or culturing, which is developing the acid content of the cream. (Only cultured cream will produce butter with a good "butter flavor".) Experience will teach you when your cream smells too sour or too ripe, and when it's just perfect. I usually set the cream on the drainboard after breakfast and make butter after supper the same day.
For this step, it's imperative that you use a jar which is only 1/3 full. (If you need to pour your cream into a larger container at this point, do so.) The "empty" two-thirds of the jar allows the cream to expand as you shake it ... and also allows the thick fluid to splash against the walls of the container more violently when the jar is shaken. (This splashing — technically known as concussion — is what turns cream into butter. It is the same action of churning, but without a butter churn.)
OK. Now sit down in your favorite chair and start shaking the 1/3-full jar of ripened cream, keeping in mind that concussion is what makes the butter form. Practice agitating the jar so that a heavy impact occurs between the cream and the walls of the container.
The length of time you'll have to shake the liquid before you'll begin to see butter depends on [a] the cream's temperature, [b] the enthusiasm with which you agitate the jar, and [c] the amount of cream in the container. Hence, it's better to look for butter rather than to try to make it "by the clock." (In case you're wondering, though, you'll usually have to continue shaking for 15 to 30 minutes.) What do you look for? Just before you get butter, you'll notice that the churned cream is becoming "heavy." Then you'll begin to see a definite separation between the buttermilk and a heavy mass of butter.
At this point, you don't really have butter yet, but you're very close so keep right on shaking the jar with somewhat less vigor. Within seconds, the heavy mass will turn yellow, become firm, and separate from the milk. Do not shake the jar much beyond the point where the butter has formed into slightly firm granules. (Unless you want a harder finished spread.)
Return to the kitchen now and strain the butter from the buttermilk with the aid of a colander or other straining device. (And save that delicious buttermilk!) Then, while the solids are still in the colander, rinse them thoroughly with cold water. (Warm water will make the butter soft ... the warmer, the softer.) Your butter should now be crumbly, rather than a firm, solid mass.
Next, put the cultured butter in a bowl. (The size of the bowl will depend, of course, on how much butter you have. I sometimes save several days' cream for one large batch, in which case I need something larger than a cereal bowl.) With clean hands, work the butter around the sides of the bowl and tip it to one side to let the water run out.
After you've "worked" the water out of the butter, and the mass has become fairly firm, sprinkle some salt over it (I use about a half teaspoon of salt per half pound of butter). Work the salt in, turn the butter over, and work it in some more. Taste the butter, and if necessary, add more salt.
All that's left now is to put your lusciously creamy homemade spread into a covered container, place the buttermilk in a capped jar or bottle, and store both containers in the refrigerator until needed. (Note: If I know we'll be using our butter within an hour or two, I'll leave it on the drainboard to keep it soft and spreadable.)