What is Lye?

Created Date: 2017-05-09 Hits: 809

During a previous blog post we discussed how natural soap is made but we only briefly touched on lye… here we give you an insight into what makes oil turn into soap!

The magic ingredient is called by several names: Lye, Caustic Soda, or Sodium Hydroxide - all are accurate!


Sodium Hydroxide is a key ingredient in soap making. It is a base which means it is highly alkaline so it can cause serious burns. Lye must be treated with respect, forget that at your peril! I have had only one minor lye burn in my years of making soap and it really did burn! By adding Sodium Hydroxide (lye) solution to carefully calculated oils ensures a process called saponification happens and 'Voila' the end result is wonderful natural handmade soap enriched with glycerin!

Natural Liquid Soap uses a slightly different alkaline called Potassium Hydroxide but the process is quite similar.

Many years ago Sodium Hydroxide was made by allowing water to filter through ashes or by boiling those ashes. These days Lye is manufactured commercially and this allows anyone working with it to know its actual alkalinity and strength which makes the soap making process much safer.

Lye has all sorts of uses from food preparation to household cleaning. I have even heard of it being used to remove ink from bank notes to enable illegal counterfeiting! I just use it for soap making! Promise! 

As you can see even the most natural of soap makers need to use Sodium Hydroxide as it is the chemical that creates soap! So when buying natural handmade soap it is very important to keep your skin safe and buy from a reputable and registered soap maker. Remember, if the soapmaker has done their job properly there is no Lye left in your soap! Check soapmakers are registered with the EU or even easier check out the members section on the Guild of Craft Soap & Toiletry Makers website!

Thanks for Reading: Louise@2Sisters