How to Make Goat's Milk Soap

Goat's milk soap
Rachel Strohm/Flickr CC 2.0

Making Homemade Goat's Milk Soap

The materials for making soap with goat's milk
David Fisher

Goat's milk soap is one of the most popular homemade soap recipes and it's easy to see why. Goat's milk makes a lovely, creamy, soap that is rich in moisturizing caseins, vitamins, and ingredients that balance the skin's pH and promote exfoliation.

Making soap with goat's milk takes a bit more preparation and time than a typical soap recipe, but it is worth the trouble.

There are three forms of milk you can incorporate into your soaps:

  1. Fresh goat's milk
  2. Powdered goat's milk
  3. Canned (evaporated) goat's milk

Each requires a slightly different technique.

Using Fresh Goat's Milk

Ice Bath for Lye Solution
David Fisher

The main challenge in using fresh goat's milk in place of water in your lye solution is that as the lye heats up, it caramelizes the sugars in the milk, turning it a bright orange color. The soap ends up being a light orange-amber color. Most people prefer a whiter soap, so they go through a few steps to minimize the orange color.

The most common method is to keep the lye solution cool as you're mixing it. Start by putting your lye pitcher into a large bowl of ice water. This ice bath will help keep the solution cool to prevent the sugars from caramelizing.

Freezing the Goat's Milk

Slushy Goat's Milk
David Fisher

Start by measuring enough goat's milk to equal the amount of water in your recipe. Put it in ice cube trays or a Ziploc bag and freeze it to a slushy consistency. Break up the frozen milk and put it in your pitcher. Stir until it's slightly slushy and then start adding your lye, little by little, very slowly.

Wait several minutes between adding more lye.

You don't want the temperature to get much higher than 90 degrees. Keep adding small amounts of lye to the mixture until it's fully incorporated. For a normal batch of lye-milk, this will take about 10 to 15 minutes.

Mixing Lye With Goat's Milk

Finished Lye-Milk Solution
David Fisher

Even keeping the lye solution cool, you'll still get a bit of orange color. Part of this comes from the goat's milk itself and part of this comes from the lye heating the milk. The purpose of the ice bath is to minimize the color shift, not prevent it altogether.

Once the lye is mixed with the milk, make your soap as you normally would, using the milk-lye solution in place of your water-lye solution.

Using Powdered Goat's Milk

Powdered Goat's Milk and Oil
David Fisher

Another way to make goat's milk soap is to use powdered goat's milk. Many people swear that fresh goat's milk is by far the best, but in its absence using a high-quality powdered goat's milk should work just fine. Since it's a lot easier, some soap makers prefer it. This method also minimizes any orange discoloration.

Check with the vendor of the milk you're buying to find out the concentration, then add enough powdered milk to make the same amount as if you were using fresh goat's milk. 

As you are measuring your oils, separate 2 or 3 ounces of oil and mix the milk into it with a whisk. Stir briskly to dissolve all the lumps. Set it aside to add at trace.

Adding Goat's Milk Solution at Trace

Adding Goat's Milk at Trace
David Fisher

Make your soap like you normally would, except at a very light trace add the milk-and-oil mixture.

Stir well and pour into molds.

Using Evaporated Goat's Milk

Frozen Evaporated Goat's Milk
David Fisher

Many canned goat's milks are evaporated. To make regular strength goat's milk, add an equal amount of water. Using evaporated goat's milk in your soap is like a combination of using fresh and powdered milk when it comes to technique:

  1. Make your lye solution using half of the water called for in the recipe. For example, if your recipe calls for 8 ounces of water, make it with 4 ounces. Be careful with this solution, as it will be very strong. If the lye doesn't dissolve completely, you can add a few more tablespoons of water, a bit at a time, until it's dissolved.
  2. Use goat's milk for the other half of the liquid called for in the recipe. So, if your recipe calls for 8 ounces of water, use 4 ounces of water to make the lye solution, and set aside 4 ounces of evaporated goat's milk to use later.
  3. Mix your soap as you normally would, but when it comes time to add the lye solution to the oils, add the liquid goat's milk first. Stir it well.
  4. Then, add the double-strength lye solution to the mixture and stir until it reaches trace.

You may get a little bit of orange color shift using this method, but not too much.

Differences in Goat's Milk Soap Colors

Goat's Milk Soap
David Fisher

The color differences between the above methods are small. The batch on the left used liquid goat's milk in an ice bath. The batch on the right used powdered goat's milk. Part of the orange color is from the actual color differences in the milks: goat farmers say that the color can even change depending on the season.