You can use liquids other than water to make the lye solution for your soap. Perhaps the most popular alternative liquid is goat’s milk, which makes a lovely, creamy, moisturizing soap, but soapmakers also use coconut milk and even buttermilk. You can use milk, coffee, green tea, wine, and beer, but you need to be extra careful.
Different liquids will react to lye differently than plain water. You might have the soapmaking process down pat when using water, only to be surprised that when adding coffee to your lye instead, you end up with a foul-smelling brown soup. The good news is that the smell doesn’t remain in the final soap, but the moral of the story is to expect the unexpected when you're substituting the water in your lye solution and work slowly and carefully.
There’s a lot of debate as to whether the healing or moisturizing qualities of the liquid actually survive the reaction with the lye; some do and some don’t. But even if they don't, using a liquid other than water adds interest, fun, and a personal touch to your soap.
Using Other Liquids in Lye
Here's how to make a lye solution with tea, coffee, wine, beer, or any other clear liquid, follow the steps below. (Making a lye solution with milk or any other opaque liquid, is a little more tricky and won't be covered here.)
- Make the lye, including all of the safety guidelines.
- Place your lye pitcher inside of a roasting pan or in the sink to mix it. This way, if it does bubble over, the lye solution won’t go onto the counter or floor.
- Make sure your liquid is well-chilled before mixing the lye into it. (This is a good idea even if you're just using plain water.)
- Work in an area that has very good ventilation. The fumes from the mixture will be heavy and foul-smelling.
- If you’re working with a carbonated beverage, like beer, make sure that it is completely flat. Leave it out on the counter for several days, stirring often.
- If you're using a liquid that contains alcohol or that has a high sugar content, you may want to do a small-batch test first. Sometimes adding liquids containing alcohol or large amounts of sugar can cause odd chemical reactions in the soap batch. At the very least, it's going to make the gel stage very hot. Don't insulate these batches––they'll cook quite well on their own.
- Work very slowly, especially if this is the first time you’ve used this particular liquid in your soap. Add the lye slowly. Stir slowly.
- Take notes for next time. Soapmaking means constantly learning and employing new techniques based on your previous experiences.
Other than working slowly and following the guidelines above, the rest of the process works the same as mixing lye with plain water.