What is lye and why is it used in soap?

Lye is a very-alkaline product that is used to make soap, but it is also used in the food and cleaning industries.

There are several types of lye, the most known and most commonly used being NaOH, sodium hydroxide, and KOH, potassium hydroxide. According to the Food and Drug Administration (FDA), soap isn’t soap unless it contains an alkali such as lye. And the only alternative to lye is potassium hydroxide. You can use this chemical when making soap, but it won’t produce a hard bar of soap. Instead, soaps made with this alternative chemical are soft and liquid.

Uses of Caustic Soda or Lye

Lye is used for soap making, candle making, homemade biodiesel, frosting glass, and in making several foods. Lye is used in making things like pretzels, bagels, cured fish, olives, hominy, and canned mandarin oranges. A lye is a metal hydroxide traditionally obtained by leaching wood ashes, or a strong alkali which is highly soluble in water producing caustic basic solutions. "Lye" most commonly refers to sodium hydroxide NaOH, but historically has been used for potassium hydroxide KOH.

The History of Lye

Before you could buy lye in a bottle, people used to make it from raw materials. They used it for tanning hides and making soap.To make lye, they would burn hardwoods at high temperatures to make white ashes. Then, they used a mixture of water and baking soda to penetrate the ashes and help remove the lye from them. Next, they filtered out the ashes. That left them with water that held enough lye to make soap and dissolve the fat from the animal hides.

Now hold on a minute my friend makes lye free soap...

I hear this often.. Not true! not to be mean, this is just a case of misinformation.. If you don’t want to physically touch the lye but still want the experience of making soap there are ways that you can make and customize your own soap without handling the lye. By using a pre-made melt-and-pour soap (also known as hand-milled soap) that has been pre-saponified (in other words, the lye has already been handled). It is not lye-free, but you won’t have to handle the lye yourself. Don't forget No Lye, No Soap, there’s a huge difference between “made with lye” and “containing lye.

When you use melt-and-pour soap you can add scents with essential oils, or add other ingredients like clays, salts, or other add-ins if you want to create a personalized soap. Again, it isn’t lye-free and you haven’t technically “made” the soap but it is a way to have the experience without having to handle the lye (but it is also much less cost effective). Lye “Alternatives” Still, some soap makers make a point of positioning themselves as lye “alternatives,” insisting – for example – they use glycerin, instead, or make their soap without the involvement of lye. In both these cases, misinformation seems to be a factor.

Glycerin is a natural result of saponification and the first step in creating bases for melt-and-pour soapmaking – the most convenient home-based process – is saponification. Understanding chemistry can go a long way. As negative as some perceptions of lye can be, all soap is made with lye – whether it’s bar or liquid – and soap made well can be great for your skin.

The distinction between soap and commercial cleansers is especially clear with liquid soaps. Since most aren’t made with lye, what you’re buying isn’t soap, but a factory-made detergent for the skin. You may notice too they are often called beauty bars or body bars, not Soap bars.

Perceptions have their own power, and they can cause consumers to avoid products they might otherwise use. But perceptions can also be changed. Lye isn’t a villain, nor is soap made with lye something to avoid. In fact, in the hands of good soap makers, it’s a product made with your skin and health in mind, and is far superior in overall quality and gentleness to commercial, non-soap cleansers. It’s what you should be using.

What are the uses of lye soap?

Lye is used in the making of all soaps. During the process of changing the oils into soap, called saponification, all of the lye is used up in the finished product. It is during the saponification process that natural glycerin is created. ... That is why Lye Soap is pure soap and very good for your skin.

Why is lye used in soap making?

The chemical reaction of making soap, called saponification, is complete, the lye and oil molecules have combined and chemically changed into soap and glycerin. If the soap is made properly, the lye is used up in the saponification process to turn oil into soap.

What is the role of sodium hydroxide in soap making?

When sodium hydroxide beads or flakes are mixed with a liquid, a lye solution is created. This solution, when mixed with fats and oils, will cause a chemical reaction called saponification. The result of saponification is beautiful handmade soap. ... Sodium Hydroxide is commonly used in the formulation of bath products, cleansing products, shampoos and shaving products. Sodium Hydroxide is also used to hydrolyze fats (as in saponification) and form soaps.

What kind of lye is used to make soap?

Lye, also known as sodium hydroxide, is a key ingredient in the soap making reaction called saponification. Although this chemical is essential to produce mild handmade soaps, the substance in an unadulterated form is extremely alkaline and caustic. Sodium hydroxide is leached from wood ash using water.

Don't forget No Lye, No Soap... and there’s a huge difference between “made with lye” and “containing lye.

All soap is made with lye. Either sodium hydroxide is used for hard bar soap or potassium hydroxide is used for liquid soaps. There is no substitute for lye. Nothing else will make oil become soap.