The process of making old fashioned lye soap can be a “dirty” business. Lye soap, the type pioneers made, is very basic, but the process would make a great science project. The ingredients are simply lye (made from soft water) and animal fat. That is it.
Now, the science comes into play. To make lye, pioneers poured rain water through hard wood ashes. This process was repeated, with the water becoming more acidic each time the water passed through the ashes. When an egg floated in the water, the lye was strong enough for soap making. Rendered animal fat was then added to the lye. The mixture was left to cure for a week. During this time, a chemical reaction occurred with the resulting product being soap. It is important during the curing process to not touch the soap, as chemical burns may result.
Times have changed. Today, we have many types of soap, such as detergent and soft soap. No longer do we use only animal fats as the base. Glycerin based soaps are safer to use, gentler and smell much better.