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What is Lye

Updated: Sep 7, 2023

making handmade soap
Using Lye in Soaps

What is Lye

Lye is the scientific name of Sodium Hydroxide which is chemical made of pure salt. It is a VERY caustic ingredient so must be used with total respect. If any crystals of Sodium Hydroxide get onto your skin it will burn, it can also burn through clothing so great care must be taken when using this product.

How is lye made

It's quite a simple method really, pure salt is disolved in cold water. As the crystals of salt begin to fall to the bottom graphite rods are inserted and electricity is charged through them - crystals are formed on the rods.

The liquid is then allowed to evaporate leaving the crystals behind. These crystals are Sodium Hydroxide.


When using Sodium Hydroxide always wear protective eye glasses, gloves and long sleeves. Use in a well ventilated room and keep away from children and animals. If you accidently burn yourself with the Sodium Hydroxide, wash off immediately – some people use vinegar to wash in as this is an acid which neutralises the alkaline solution. If in any doubt whatsoever seek medical attention.

In my workshops I do put this into perspective by saying we boil a kettle of water probably several times a day and this can also cause terrible burns if poured over the skin!

Please just take great care and no accidents should occur.

When adding to your chosen liquid do not stand over the measuring jug as fumes are released for about 30 seconds and although these are not harmful they do catch in your throat if inhaled making you cough.

Using Sodium Hydroxide in cold-pressed soap

The sodium hydroxide is gently poured into a liquid and stirred until completely dissolved. This will heat immediately to about 200f and should be placed in cold water to reduce the heat.

The liquid may be one of many things i.e. water, milk, beer, coconut water, almond milk, herbal teas, sea or salt water, floral waters etc.


Always pour Sodium Hydroxide into your liquid NEVER the other way round as you can cause a volcano effect which could be dangerous

Can I make cold-pressed soap without using a lye?

The simple answer to this is no.

Lye is an essential part of the chemical equation needed and without it you can not make soap.

Sodium Hydroxide (NaOH) is used for making solid bars of soap and Potassium Hydroxide (KOH) is used to make liquid soap.

Why does commercial soap make your skin dry and tight

In soap making glycerin is produced, this is a humectant, meaning, water from the air is grabbed and locked into your skin, this is naturally moisturising. Handmade, artisan soaps will contain glycerin, however, when made commercially it is often removed and sold to make other things such as fertilizer and explosives.

What is saponification

This is a chemical process by which triglycerides in oils/butters react with sodium hydroxide.

Soap Making Fun

Come along to one of the workshops and make your own soap to keep or do our Soap Making Online Workshop (coming very soon).

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