So last week I was talking about lye in soap and why it has to be there. Did you know that lye is actually a natural product? It's sodium, oxygen and hydrogen atoms. It 's found in nature, but we usually purchase it from a lab because that way we can make sure it's pure. When it comes to us, it's dry flakes and we combine it carefully with water when we are preparing to make soap.
When we add the sodium hydroxide to the water, a reaction occurs creating a lot of heat. Sometimes the water will get as high as 200 degrees Fahrenheit during the reaction. As it combines, the pH also gets very high and it becomes dangerous to handle. Don't worry, though, we are very careful and take precautions.
Once the lye has cooled off some, we can combine it with the oils and butters. We stir and stir and stir some more making sure that the lye combines completely with the oils. The weight of the mixtures have to be carefully calculated so that the lye breaks down completely with just enough oil left over so that it doesn't dry out the skin. We don't want any lye left over at the end of the process because that would burn skin. It takes lots of practice and trial and error to get the measurements just right.
Next week, more information on the butter and oil side in What's in soap? Part 3