One example of a dish soap recipe combines 1 1/2 cups water, 1/4 cup grated bar soap, 1/4 cup liquid castile soap and 2 1/4 teaspoons super washing soda. It also calls for 1/2 teaspoon vegetable glycerin and 15 to 40 drops of essential oil.
To make liquid dish soap, dissolve the grated bar soap in the water over medium heat. Once the bar soap is dissolved, remove the mixture from the heat. Stir in the liquid castile soap, super washing soda and glycerin. Pour the soap mixture into a jar or container to cool. Then, allow the mixture to set for up to 24 hours.
The mixture thickens as it sits. However, if a thicker consistency is desired, simply reheat, and stir in an additional 3/4 teaspoons of super washing soda. If the consistency of the mixture is thicker than desired, stir in 1/4 to 1/2 cup hot water. To smooth the consistency of lumpy mixtures, run the soap through an immersion or handheld blender. When the soap has reached the desired consistency, stir in any desired essential oil for fragrance or added cleansing capability.
This soap recipe is intended to be used for hand-washing dishes only. It should not be used in dishwashing machines.