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  • Writer's pictureGina Reid

The Truth About Lye

OR What's that chemical doing in my natural soap?

One of the big questions I get asked is, what about the lye in your soap? Isn’t it harmful? I thought your soap was “natural”, why are you using chemicals?

All good questions, I’m glad you asked!

First up, what exactly is lye? Lye is also known as caustic soda or sodium hydroxide.

Sodium hydroxide is a pH balancer used in a wide range of beauty and skincare items, like cleansers, soaps, makeup, and creams or lotions.

It is highly alkaline. In fact, it rates at nearly 14 on the pH scale.

Scale: 0 (very acidic) to 14 (alkaline, or very basic).

This matters because your skin has a more acidic pH. Skin generally falls somewhere between a 4 and 7 on the scale. It’s important to maintain your skin’s natural level of acidity in order to keep moisture in and help protect your skin from damaging elements, such as bacteria, environmental toxins and pollutants.

With an unbalanced skin pH, you could have a higher chance of:

  • skin conditions, like acne

  • itchy and dry skin

  • changes in skin pigmentation

  • fine lines and wrinkles

Sodium hydroxide is overall considered safe for general use - but only in small amounts, at lower concentrations.

Sodium hydroxide also plays another important role in a chemical reaction that transforms fats and oils into a smooth, well-mixed soap.

Ancient Mesopotamians were the first to produce a kind of soap. They did this by cooking the fat rendered from an animal, together with water and lye, traditionally obtained by leaching wood ashes,

You can only imagine the result!

A greasy and smelly goop, but one that helped lift away dirt.

We are a lot more sophisticated today and our sodium hydroxide is developed in a laboratory. Once diluted with water it creates lye or lime water.

You cannot make soap without lye as it is a vital part of the chemical process, and it also holds or maintains the pH of the soap.

Cold process soap (which is what Luxi Buff soaps are) is made by combining oils and sodium hydroxide mixed with water (lye water), which causes a chemical reaction called saponification.

Say what?


Saponification is the chemical reaction during the soap-making process in which the fats and oils react with lye to form soap. The lye helps the oils and fats lather and foam into a soap. Without it, your soap would be a big mess of various oils and fats that aren’t unified into one product.

The word Saponification literally means "turning into soap" from the Latin root word, sapo, or soap. Glycerin and soap are the results of the saponification reaction. These can be separated out (as is the case with many commercial soaps) or left together as with Luxi Buff soaps to create a creamier moisturising soap.

Base (lye) + Acid (fats and oils) = Salt (Soap + Glycerin)

*(See the blog post on 4 epic reasons to use handmade soap)

The saponification process generally takes about 24 to 48 hours to complete once the lye and oils have been mixed and the raw soap has been poured into the mold.

This process can be sped up by adding more heat or slowed down by keeping the process cold. The soap is then left to cure for 4-6 weeks. Over this period, it loses water weight and the soap gets harder.

As long as the ratios of oils, butter, and lye have been calculated correctly, there is NO MORE lye left in the soap at the end of this process. Hence on the ingredient list is written… saponified cocoa butter, coconut oil…etc

So there you have it. Hopefully, you have a better understanding of the process it takes to make your soap, and that while lye is needed to make your soap, it is not present in the final product and has no cause for concern.

Thanks for hanging in there and reading to the end!

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