Soap milling, also called French Milling, is an easy traditional process for enhancing cakes or bars of soaps. Milling allows you to add a variety of healing, soothing, or cleansing ingredients, such as extra fats or oatmeal or essential oils, to  your soaps. I like to make hand milled soaps to give as gifts as well as to add luxury to our daily lives.

I’ve used two methods for hand-milling soaps. This method uses heat and works better for soaps you intend to mold. The second method uses warm water, making it a terrific method for kids, and works better for making soap balls and hand-sculpted bars.

Milling Soap Tutorial

This is a basic procedure, not a recipe. I haven’t included specific measurements but have instead described the process and what to look for as you’re working. For specific recipes using this technique, see The Practical Herbalist Recipes.

Equipment you’ll need to mill soap:

  • a mixing bowl
  • a cheese grater
  • a non-reactive pot
  • a rubber scraper or a spoon
  • soap molds
  • waxed paper (optional)

Ingredients for milling soap:

  • One or more bars of unscented, natural soap
  • 1/2 cup of warm to hot water for every 4 ounces (approximately 1 cup, grated) soap
  • essential oils, herbs, abrasives, or other ingredients

Procedure for milling soap:

  1. Grate the soap into a mixing bowl.
  2. Add water, approximately 1/2 cup per 4 ounces of soap, and stir well.
  3. Heat the mixture on low setting, stirring constantly until the soap is melted and thoroughly combined with the water. It should be about the consistency of a soft cookie dough.
  4. Remove the mixture from the heat.
  5. Add any further ingredients, such as herbs, honey, or abrasives. Do not add essential oils yet because the heat will cause them to evaporate.
  6. Stir the mixture until it’s cool but still pourable.
  7. Add any essential oils and stir thoroughly. Try adding 4 or 5 drops of essential oil for every cup of soap you grated.
  8. Spoon into molds, pack the soap well so there are no air bubbles.
  9. Set the molds aside to dry and harden.
  10. Once the soap is hard enough, turn it out of the molds and set it on a wire rack or waxed paper to harden thoroughly. This may take a few weeks.

Finishing and Storing your Hand-milled Soap

After your soap has dried and hardened thoroughly, which may take as much as a few weeks, store it in an air-tight container. It will last for a long time, but after a few months any scent you have added to it may lessen. You can re-mill the soap to add more essential oils to it, if you wish.