When is Lye no longer toxic

by Angie

Question: at what point does the lye no longer hold caustic properties. Why is it safe for soap making as well as for other toxic components.

We are first time soap makers with children being a part of it and just want to have the full picture.


Lye (sodium hydroxide) is always caustic in the flake/bead and liquid form. It only ceases to be caustic when it is no longer lye.

In the soap making process you need a certain amount of lye solution and a certain amount of oil in order to make soap. Once the lye and the oil are mixed they combine in a chemical reaction called saponification which results in a new product - 'soap'. This reaction takes some time to complete. Once the lye solution and the oil have been mixed together and blended until they trace (become thick) the mixture is poured into a mold and insulated so that the chemical reaction can continue. I do not know exactly at what point the chemical reaction is complete but typically soap is left to cure for 4 - 6 weeks after it is made. This ensures that the chemical reaction is finished and that the soap is gentle for skin use.

I've often used soap that is only a week old and I can honestly say that it tends to be quite drying to the hands whereas soap that has cured properly is not drying at all.

If you include children in the soap making process be extra sure that you use all the necessary safety equipment and precautions. I strongly suggest becoming familiar with the process yourself first and then having at least one adult per child when you include them in the process.


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Lye and Pregnancy
by: Caroline

So does that mean lye soap is non toxic if bought from a reputable source? Is it safe to use on skin while pregnant?

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