While lard isn't considered a food, it was vital to the cooking process for many years. Here is a brief description of this necessary pioneering activity.
"A 225-pound hog will yield about 30 pounds of fat that can be rendered into fine shortening for pastries, biscuits, and frying. The sheet of fat just inside the ribs makes the best quality, snowy-white lard. This “leaf” fat renders most easily, too -- and is ninety percent fat. The “back” fat, a thick layer just under the skin, is almost as good, giving about eighty percent of its weight in lard.
A slow fire and a heavy pot that conducts heat evenly are most important in making lard. Put ¼” of water in the pot to keep the fat from scorching at first. Remove any fibers, lean meat, and bloody spots from the fat, and cut into very small pieces. It’s not necessary to remove pieces of skin, but many people prefer to. Put a shallow layer of fat in the pot. When the first layer of fat has started to melt, add more. Do not fill the kettle to the top -- it can boil over too easily. Stir frequently and keep fire low.
The temperature of the lard will be 212F at first, but as the water evaporates, the temperature will rise. Be forewarned that this will take a long time at low heat and that you must stir the lard frequently to prevent scorching. As the lard renders, the cracklings will float to the surface. When the lard is almost done and the cracklings have lost the rest of their moisture, they will sink to the bottom. At this point turn off the heat and allow the lard to settle and cool slightly. Then carefully dip the liquid off the top into clean containers. Strain the cracklings and residual liquid through cheese cloth. Fill containers to the top -- the lard will contract quite a bit while cooling. Chill as quickly as possible for a fine-grained shortening.
Air, light, and moisture can make lard rancid and sour. So after it has been thoroughly cooled, cover the containers tightly and store them in a dark, cool area.