If you follow my Facebook page then you may well have read an early version of this post. When I make my soap (and in my skincare range) I choose to only use natural ingredients. This means no synthetic colours or fragrances.
Every so often I get the question “if your soap is made with only natural ingredients why does it have sodium hydroxide in it?”
The short answer is that you can’t make soap without sodium hydroxide (also known as lye) – it binds the oil and water together during the soap making process. This same process, and the curing time afterwards, neutralises the lye.
Back when our great-great-grandmothers made their own soap the process wasn’t radically different from today. Soap was made by mixing animal fat with water that had been passed through wood ash from the fire. When water is filtered through ash the end result is lye. The big difference between now and then is that great-granny couldn't be totally sure how strong her lye was and could end up with soap that could be quite harsh, very gentle, or somewhere in-between.
We now have the advantage of being able access lye knowing exactly how strong it is and can then tailor soap recipes to create the perfect bar of soap with a range of vegetable oils and butters, herbs and spices.
So while it may sound “chemical” lye is the result of blending to naturally occurring ingredients – ash and water.