What is Sodium Hydroxide Lye?

Many people are afraid to make soap because of lye.  They have heard that it is dangerous and that scares them away.   Unfortunately, they never look back and learn that it is possible to work safely with lye and that it isn’t very difficult to do.

Some people might think that lye is not organic, so they want to stick with more organic products.   But every soap is made with lye, whether the label says or not.    It is not possible to get soap without lye.    Even melt and pour soaps are made with lye.

There are different types of lye.   Sodium Hydroxide is the type used to make cold processed soap.   Potassium Hydroxide can be used to produce liquid soaps such as dish soap or liquid shampoos.

Sodium Hydroxide comes in flakes or granules.  Below is a picture of the Sodium Hydroxide flakes.  The granules look like big sugar particles.   Neither is better than the other — it’s a personal preference.   I find that the granules melt easier in the water, but the crystals make less dust when you are scooping out the lye from the lye container, and it is easier to see them when they are still undissolved in the lye solution (because you will need to make sure they are fully dissolved before adding the lye solution to the oils).


So what is sodium hydroxide lye?     It is a highly caustic and alkali chemical.  It is water-soluble and can easily be made into a solution by mixing it into water.   When you add a lye solution to oils and mix it up, a chemical reaction occurs that turns the oils into soap.  This process is known as saponification.  The lye binds with the fatty acids in the oils and creates a third substance that is no longer lye, nor no longer oil — it is soap.

The danger is that when it comes into contact with skin, eyes, or lungs, it will burn you.   It can cause dermatitis, burns, rashes, blindness, lung and sinus irritation, or worse (depending on the nature of the exposure).

While all the safety warnings may be off-putting, it is fairly safe to use lye if you take some basic safety precautions.

You do things every day that require you to use safety precautions.   Take boiling noodles for an example.   You will be using a stove. That can be dangerous – it gets very hot.   Boiling water is also dangerous.  If you don’t turn that pot handle to the side, it could be bumped and spilled on someone.    If you grab a hot pan handle without hot-pads, you will get burned.   If you are not careful when draining the water out of the noodles, it can splash and burn you. If you don’t turn off the stove, you can catch the kitchen on fire.   So many dangers!   I bet you do it all the time though and don’t even have to stop to think very much about the safety procedures for doing so.  It just became second-nature at some point in your past and now it is just business as usual for you.    After working with lye safety precautions for a awhile, it will be the same.  You will  incorporate the safety procedures into your soap making routine and barely think about them at all.

Below are some general safety guidelines and first aid procedures for working with lye.  These are not intended to provide a thorough education or medical advice.  They are just a few safety guidelines that most soap makers follow.

Some Guidelines For Working Safely with Lye:

  1.  Clear the area of any children, pets, or people who are not wearing safety gear.  Keep them away until you are done with the cleanup steps at the end of your soap making session.
  2. Put on safety gear (eye protection, nitrile gloves, and covered skin such as long sleeves, socks, pants, and shoes).
  3. Open a window for ventilation, or work outdoors or in a well-ventilated location to avoid build-up of fumes.
  4. Always add lye to liquid and never the other way around.   Adding liquid to lye will cause a violent volcanic reaction that can splash and injure you.
  5. Use only microwave safe glass or plastic as your mixing containers.   The saponification of the lye and oils can cause high heat.
  6. Use only silicone, plastic or stainless steel for anything that will come into contact with the lye or soap batter.   Some metals, such as aluminum or  galvanized tin, can make a chemical reaction that can cause explosive hydrogen gas to occur.  Wood can splinter over time and cause splinters to get into the soap batter.
  7. Store the lye in a place that is not accessible by children and pets, and where it won’t be mistaken for food.
  8. Keep any implements that come into contact with the lye or raw soap batter separate from your cooking implements to prevent cross-contamination.
  9. Clean up any spilled liquid or particles immediately so that you don’t accidentally contact it, and kids or pets don’t get exposed to it.
  10. Use a well-labelled container to hold the lye solution so that it is not mistaken for water.  It also helps to keep the lye solution container in the kitchen sink so if it should spill, it will be contained and easy to clean up.

If you do spill any lye, then know ahead of time how to clean it up and/or treat the injuries.

If you spilled flakes or crystals:

  1. While wearing the safety gear, pick up the particles with a damp paper towel.  Make sure to get all of them picked up, even the dust. Dispose of the paper towels in a  sealed plastic baggie.
  2. Wipe with a wet wash cloth.  Wring it out and wipe again.  Do this a third time.  Put the wash cloth in the laundry and do not reuse it for cleaning dishes until it is washed.
  3. Spray with household vinegar to neutralize any remaining lye.

If you spilled lye liquid or soap batter:

  1. While wearing the safety gear, sop up the liquid with a rag or paper towels.   Soak up as much as possible.  Dispose of the rags or paper towel in a sealed plastic bag.
  2. Wipe with a wet wash cloth.  Wring it out and wipe again.  Do this a third time. Put the wash cloth in the laundry and do not reuse it for cleaning dishes until it is washed.
  3. Spray with household vinegar to neutralize any remaining lye.

If you get lye on yourself:


  • Flush with plenty of clean water for 15 minutes, making sure to get under your upper and lower eyelids.  Call a physician.


  • Rinse and flush with plenty of clean water for 15 minutes.  If irritation persists, consult a physician.
  • DO NOT douse the skin with vinegar, at least until after you have rinsed it for 15 minutes with water.  Vinegar is an acid.  When it comes into contact with an alkali, such as lye, it will create immense heat and cause the burns to intensify.
  • Treat burns as you would any burn.


  1. If you spill lye on your clothing, remove the clothing and flush the skin with water as described above.
  2. Wash and dry the clothing before re-using it.


  1. If the lye dust is irritating you, wear a dust particle mask.  These can be bought at a hardware store.
  2. If the lye fumes are irritating your lungs, provide more ventilation by opening another window or employing a fan.   If it is making you short of breath or ill, remove yourself to a location with plenty of fresh air, such as outdoors.   If irritation persists, seek medical care.


  1. Do not induce vomiting.  Seek immediate medical attention.


Educate yourself on lye safety:

A couple of good resources for learning about lye safety are:




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