Making Soap

How to Make Lye Solution for Soap Making

If you are thinking of making your very own homemade soap, you must have gone through many soap making recipes. In all of the soap making recipes, you must’ve seen that they are combining lye and oil with some additives that cause a chemical process known as saponification. This results in the soap we use. 

But “How do you make lye solution?” this question must’ve popped in your mind.  Well, in this article I’m going to answer this question.

You can make your lye solution through traditional leaching wood ash or you can buy lye directly from chemical stores and mix it with water to make the lye solution.

However, this is just an overview of the processes involving making a lye solution. There are a lot of essential steps and safety measures that need to be taken care of. Knowing and understanding these steps are important in making a good lye solution. Here is all the information you need to know before you start making your own lye solution.

What is lye?

Before you learn how to make lye, you need to know what it is. Lye is a metal hydroxide, most commonly known as Sodium Hydroxide (NaOH). Potassium Hydroxide (KOH) is also sometimes referred to as lye.

Both Sodium Hydroxide and Potassium Hydroxide are very basic alkali that is highly soluble in water. This results in a caustic basic solution. As they are caustic, their pH level is higher than 7. If they come in contact with bare skin, they can give you a chemical burn. So, taking safety precautions is a must while handling lye.

How to make a lye solution?

Mainly two methods are used to make lye. They are-

Traditional method: Our ancestors have been using this method for several hundred years to extract lye. This method is known as leaching. The lye you will get through this method is Potassium Hydroxide.

Ingredients: You only need two ingredients.

1. Ashes: Hardwood tree ash is the best for this method. To prepare the ash, simply burn wood completely and collect the remains. You can use ash from other sources, such as softwood trees, paper, but they have chemical contaminants that may be undesirable if the lye is to be used for soap.

2. Water: Use clean water that has no contamination for better quality lye.


  • Safety goggles and gloves
  • Plastic bucket
  • Cork
  • Stones
  • Straws or grass
  • Beaker

Procedure: The main thing is you soak the ash with water and collect the Potassium Hydroxide solution residue through a drain hole. 

Step 1:  Wear all the safety equipment.

Step 2: Collect a plastic bucket and drill a small drain hole at the bottom of it.

Step 3: Plug the drain hole with a cork.

Step 4: Place stones at the bottom of the bucket.

Step 5: Cover the stones with a layer of straws or grass. This serves to filter the solution from the ash.

Step 6: Add ashes and water to the barrel. Make sure the mixture is not too watery. Aim for a slurry.

Step 7: Allow the mixture to sit for three to seven days.

Step 8: Collect the lye solution by removing the cork at the bottom of the bucket. 

Step 9: Test the concentration of the solution by floating an egg on the solution. If a coin-size area of the egg floats above the surface, the lye solution concentration is sufficient. 

Step 10: If you need to concentrate your lye, you can evaporate excess water through heating the solution. 

Alternative method: You can buy Sodium Hydroxide directly from chemical stores. It can be of various forms such as flakes, pellets, or coarse powder. Sodium hydroxide is very hygroscopic. That means it attracts moisture. If it is left exposed to air, it will absorb moisture from the surrounding. As a result, it will lose its potency and your soap may not saponify fully.

Now, how to tell if the lye is bad? To answer that, the first thing you need to look at is the color of the lye. Good lye has a white color. If the lye is bad, its color will turn into grey or off-white. You will also notice that the lye will be clumpy as it has absorbed moisture from the air. So, always put lye in an airtight container and store it in a cold place.


1. Distilled Water: The solution making process will generate a lot of heat. So chilled distilled water is used to prevent the generation of excessive heat. The use of tap water is not recommended as they have many contaminations. It can react with soap molecules and make the soap insoluble. 

2. Lye flakes: Make sure you buy high purity (at least 95%), completely dry and flowable Sodium Hydroxide flakes. If you notice any sign of clumped or any color change to sodium Hydroxide flakes, don’t use it for making lye solution.

3. Additives: People sometimes add salt, sugar, or color pigments to water or lye solution to enhance their dissolution or incorporation into soap better.


  • Safety goggles and gloves
  • Gas mask
  • Accurate digital scale
  • Measuring cup
  • Heat Proof non-reactive container
  • Stainless Steel spoon
  • Thermometer


Step 1: Wear safety equipment.

Step 2: Weigh the lye flakes. Don’t keep the lye exposed to air for a long time.

Step 3: Put the thermometer into the container.

Step 4: Add the lye to the water. Never do the opposite. It will cause a rapid increase in temperature. Typically, in a lye solution, 25% is lye and 75% is water. This proportion can slightly change depending on the soap recipe you are following. Add lye flakes in small portions and stir. Keep checking the temperature to avoid excessive heat generation. 

Step 5: Add the additives to improve the dissolution.

Step 6: Stir the mixture slowly with the stainless-steel spoon until the mixture becomes completely clear. The temperature can rise up to 80 to 90°C. The hot solution releases toxic fumes. So, to avoid inhaling the fumes, use gas masks.

Step 6: After stirring, cover the top of the container and put it in a safe place to cool down. 

Step 7: Label the container clearly and put a warning sign to prevent accidental spillage and so that no one drinks it. Ingestion of lye is often deadly.

Safety Measures:

Lye is very caustic and basic. Whatever method you follow to make the solution, you have to follow some safety measures strictly. Otherwise, it can create a life-threatening situation. 

  1. Always dissolve lye outdoors or in some well-ventilated room. While dissolving lye, the solution releases toxic fumes. If inhaled, it can cause irritation to the lungs. Long term exposure can lead to lung damage.
  2. Use a gas mask to avoid inhaling toxic fumes.
  3. Always use hand gloves and goggles while handling lye. Wear long sleeve dresses to protect exposed body parts.
  4. Prevent any distractions while working with lye.
  5. Keep the chemicals away from children in a safe place.
  6. Always put labels and a warning sign to the lye and lye solution container. Place them somewhere safe so that no one can accidentally spill or drink it.


Lye solution and oils with other additives chemically react with each other and result in soap. Handmade soaps are much healthier than store bought ones that are filled with harmful chemicals. 

Making a lye solution is an essential part of the soap making process. After reading this guide “How to make lye solution?”, I think it is clear to you how you can make a perfect lye solution. I hope you found what you were looking for in this guide. Please follow the safety precautions strictly. Thanks for stopping by.