Create new soap bars from old ones using a process called milling. You can use this method to make new soaps from your leftover scraps or to add new scent and colour to plain soap. Any type of soap can be used for this method, as long as the scraps are grated together. Save your scraps until you have enough to make several new bars and you can prepare a batch of new soap for your bathroom or kitchen.
Allow the soap scraps to dry overnight; they are easier to grate when they are dry.
Rub the soap scraps on the medium side of the grater into the ceramic bowl.
Stir to combine the scraps if they are different colours or scents.
Add water a teaspoon at a time and stir. The soap is ready to mould when you can pick up a handful and press it into a ball. Soap that is ready to mould will hold together; if it is crumbly, add water.
Press the prepared soap into a mould and pack it in tightly to compress it. Let the soap dry overnight.
Pop the soap out of the mould and let it cure on a countertop for a week. Curing is not mandatory, but will make your new soap last longer.
It's OK to wash the grater and reuse it in the kitchen. Add scents or colours to the soap before you mould it.
Don't add too much water to the grated soap; use just enough to make it hold together.