The amount of lather your homemade soap produces is directly related to the types and balance of oils in your soap recipe. Different oils give different amounts and different types of lathers, so many soap makers turn to sugar to increase the suds.
Adding a bit of sugar to a soap recipe can help make a light, bubbly lather with large bubbles when the oils you're using do not lather up as much as you'd like. There are three ways to augment your recipe with sugar during the process of soap making.
Add Sugar Before the Lye
The easiest method is to incorporate the sugar while making your lye-water solution. Add sugar to your water and make sure it is completely dissolved before you add the lye. If your soap recipe calls for it, this might be a good time to add salt to the water, too.
As for the ratio of sugar-to-water, you want 1/2 to 1 teaspoon of sugar per pound (16 ounces) of oils. For example, if you are using 32 ounces of oils, you'll want to add 1 to 2 teaspoons of sugar. If you are using 48 ounces of oils, add 1 1/2 to 3 teaspoons of sugar, and so on.
Sometimes the heat of the lye solution will begin to caramelize the sugar a bit and turn the sugar water a bit of a beige color. It will not be quite like the orange color you get with goat's milk soap, but the sugary solution turns that color for the same reason. This is just an aesthetic consideration as it does not affect the constitution of the soap at all.
Add Sugar to the Lye Solution
Another option is to add sugar directly to the lye solution:
- Separate a few ounces of the water you have weighed to make your lye solution.
- Add 1/2 to 1 teaspoon of sugar per 1 pound of oils you are using to the water (the same ratio as the first method).
- Stir until it is completely dissolved (sometimes it helps to warm the water first).
- Add this sugar-water solution in at trace with your other additives, but before the fragrance oil.
Add Sugar Syrup at Trace
The third method has you make a “simple syrup.” This is a solution of water and sugar prepared ahead of time by mixing 2 cups of sugar and 1 cup of water and slowly heating it on the stove. Stir it gently until all of the sugar has dissolved. Let it cool and pour it into a bottle that you use when making soap.
Add 1/2 to 1 teaspoon of the syrup per 1 pound of oils (the same ratio as the other methods) to your soap mixture. Again, do this at trace with your other additives, but before adding the fragrance oil.
Sugar May Heat Up Soap
While sugar has its benefits in soap, there is a word of caution as well. Some people have noticed that adding sugar to their soap makes it heat up and speeds the saponification process to the gel stage.
The same thing happens when milk is added; the sugars in the milk are jump-starting the gel process. Just be careful if you are adding both sugar and milk to your recipe because your soap can get quite hot.