Various forms of soap are made from the crutcher. These include soap bars, soap flakes, and powdered soap. The type of soap depends on the raw ingredients put in the kettle. Animal and vegetable fats are common mixtures. Hard soaps that do not lather in cold water are produced from animal fats, such as grease and tallow.
Potassium hydroxide makes soft soaps like shaving creams.
In the 1930 s continuous processing was developed. Time and space were saved, when compared to the kettle method. It also makes it easier to recover the glycerin by-product. The fats are then pumped downward toward the bottom, and then distilled water flows in near the top. Pressure is then added to the mixture and the temperature then rises to 260 degrees Celsius.