Is All Soap Made With Lye?

The quick answer to the above-posed question is "yes".  As I outlined in a previous post about the difference between commercial "soap" and handmade soap, without the saponification process, which requires lye, you have detergent.

First, what is soap?
Soap is an alkali combined with fat.  The alkali {lye}, when added to the fat {oils, lard, butters, etc.}, goes through a reaction called saponification.  The result of the reaction is soap and glycerin.

Why is the soap not harmful if it contains lye?
Lye, on it's own, can be very harmful and should always be handled with care according to package instructions.  That being said, when lye is mixed with the appropriate amount of fats, the lye turns from a caustic substance into a nice, gentle, bar of soap.  There is concern when people hear about lye in soap, and rightly so, however, the dangerous effects of lye are completely diminished during the soap making process.  The key is in using a lye calculator which will tell you exactly how much lye is needed depending on the types of fats used.  All fats require a specific amount of lye to turn it into soap.

The next consideration is to use more fat/oil than lye can convert into soap.  This is called "superfat".  Using a superfat amount of 1-10% prevents you from having any excess lye in the finished soap and, instead, gives you a percentage of fats that aren't converted into soap and remain as an extra moisturizing benefit.

What about "Melt and Pour" soap?  I don't have to use lye for that.
Correct.  You don't have to use any lye when using Melt and Pour soap, however, it does have lye in it.  The Melt and Pour base was originally made with lye.

One concern about Melt and Pour soaps worth noting - if you are considering making this type of soap, check out the ingredients list first.  They often contain questionable ingredients.

What about liquid soap?
Any skin-washing product or shampoo made without lye is a detergent, not a soap.  They achieve a sudsy liquid usually by utilizing sodium laurel sulfate or sodium laureth sulfate as the main binding ingredient.

I just read the ingredients list on my bar of soap and I don't see "lye" listed.
Lye can be listed in a number of ways on the label.  It can be listed as "lye", as "sodium hydroxide" or "potassium hydroxide", or the oils can be listed as "saponified" or "sodium", denoting it was saponified with lye.  You may see coconut oil, for instance, listed as either "saponified coconut oil" or "sodium cocoate".

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daisy g said...

Great information!

The Woodcutters Wife said...

An informative, easy to understand explanation - thankyou.