Here’s Why You Need Lye Calculators When Making Handmade Soap

Lye Mixture

The human race has approve the idea of proper hygiene and knew how to make soap 4 millenniums ago.

The earliest evidence of soap making was found in a papyrus originating from ancient Babylon. The papyrus told of a time when everyone took baths everyday using a soap recipe, which pretty much resembles the modern era.

This is a fun fact the kids may be #shook to know. But it’s amazing how little soap making supplies have changed. It’s the same basic ingredients one may encounter in a soap making supplies cabinet: animal or vegetable oils and alkaline salts.

The only difference is a more refined technique and a lot of safety precautions. One of which is the use of a lye calculator and different methods on how to make soap. Click here to jump to other handmade soap recipes and the like!

Lye: A Brief Background

Lye: Some of us may not know what it is, but it is found in many products that we use. The scientific name of lye is called sodium hydroxide, and it is a chemical that is made from salt.

Lye is naturally available and can be used in various ways such as in food processing. For example, olives are soaked in a lye mixture to give them their distinct black color.

Lye is also used in making chocolate, processing sodas, and thickening ice cream. Other uses of lye include paint removal, paper-making, and soap-making.

Lye is an all-around product that can be used in various situations – it’s really that versatile!

Is it Normal to Use Lye in Soap?

Lye is used in soap making for thousands of years now. The basic soap recipe begins with two ingredients, namely lye and natural oils. Lye is important because it binds molecules from the air into the oils to trigger saponification.

After three to four weeks or curing, what’s left behind is pure soap, ideally with no trace of lye.

How to make soap without lye, well without lye, soap would not end up hard or dense. All handmade soap should be made with lye, but at the end of the process, there is no lye present anymore because of chemical changes.

Long ago, lye soap was initially made from wood ashes, water, and animal fat. Today, handmade soap can just contain vegetable oils instead of animal fat. Lye in itself is vegan since it does not make use of any animal products and is naturally occurring.

This is perfect for vegetarians and vegans alike! Examples of vegan lye soaps involve mixtures of lye with almond oil, coconut oil, shea butter, and palm oil.

Is Lye Soap Safe?

Making lye soap is completely safe, even for pregnant women, just as long as one follows precautionary measures when handling lye.

Some of these measures involve using gloves, eye protection, and covering your work area with newspaper when mixing lye. Lye can be dangerous to work with because it can burn the skin.

When mixing lye with water and oils, it is advised not lean over the mixture and to maintain space because even just a single drop of lye can cause pain and itching on the skin.

If ever your skin gets affected, wash it immediately with soap and water.

After using lye, it is important to fold and seal the used newspaper in a trash bag.

Pregnant Women Using Lye


Other pregnant moms also share that they wear long sleeves, long pants, elbow-length rubber gloves, and protective goggles in order to be extra safe when handling lye.

They also work outside their houses where there is more ventilation.

Safe for the Skin


Since lye is used at a very low level of concentration when making handmade soap, it is safe even for those people who have acne.

Lye is found in various cosmetics products like lotions, shampoos, and face serums; therefore, lye soaps are very safe for both pregnant women and people who have issues with acne.

Lye Substitute


There’s another variant of lye that is called KOH or potassium hydroxide and can be used as a substitute. Its alkaline level is lower than sodium hydroxide.

If you know how to make soap, you would definitely agree that sodium hydroxide is the best ingredient to make solid soap.

If you want to make a genuine handmade soap, then there is no other alternative than lye or sodium hydroxide.

Benefits of Lye Soap


Compared liquid soap, soap made with sodium hydroxide is better at breaking down dirt and oil and moisturizing the skin at the same time.

Lye soap is also more economical to make. A bath bomb recipe, for example, needs more ingredients namely, baking soda, epsom salts, and citric acid, while lye soaps would only need lye, water, and essential oils.

The ingredients needed in soap making is more accessible than those of bath bomb ingredients.

Uses of Lye Soap


Humankind has used lye soap is way before detergents and shampoos. It was used for skin ailments such as mosquito bites.

Lye soap bars are very effective as stain removers and have outstanding sanitizing properties. Additionally, it can also help in curing skin problems such as dandruff and psoriasis.

Lye Calculators – How Much Lye Should I Use?


To properly use lye in soap recipes, one needs to employ the use of a lye calculator. A lye calculator estimates how much lye should be put in a specific soap recipe.

It is important to have a lye calculator in order to make sure that there would not be extra lye in the soap after it is cured. If there is additional lye in the finished product, then it is very likely that it would irritate the skin of the user.

The lye calculator measures the saponification value or the amount of lye that is needed in order to completely saponify one gram of a type of fat or oil.

You can find lye calculators online such as Certified Lye. They have a recipe formulator in order for you to be informed of the proportions of lye, water, and oils to be used in making your own soap.

How to Make Soap Tutorial


So, how to make soap with lye?  Listed below are basic soap recipes that involve lye.

In learning how to make your own soap, there are two processes used: hot process or cold process. Both of these methods make use of water/lye mixture and essential oils.

The difference is that hot processing has an extra step of cooking the mixture, speeding up the process of saponification. This makes the soap cure in days’ time instead of weeks, which is the case when cold process method is used.

In the recipes below, the hot process is used in making lye soap that consist of fairly the same process but differ in just one ingredient!

How to Make Soap with Lard


First of all – what is lard? Lard is rendered fat that is from the abdomen of a pig that is used for cooking. To make lye soap from lard, take note of the ingredients and the method below:


– Two (2) pounds of lard

– Pure filtered water

– Lye with 0-1% excess fat (Make sure to use the lye calculator in order to determine the specific amount of water and lye needed in your recipe.)


  1. Get two separate bowls, put the lye and water on each and then measure them using a kitchen scale.
  2. Pour the lye into the water. Remember that you should never pour the water into the lye. Stir the mixture until the lye is completely dissolved. Make sure to follow the safety precautions while doing this process.
  3. Put the lye mixture under a vent and let it cool down.
  4. Get the lard and measure its weight. Place it into a crock pot and let it melt on low heat. Once the lard is melted, add the lye mixture to the oils and then stir.
  5. Blend the mixture until it forms into a thick consistency. Once it achieves this consistency, cover the pot and let the soap be further heated for about one (1) hour.
  6. Prepare your mold for the soap.
  7. Using a spoon, scoop the soap mixture into molds. Allow the soap to cool and harden for about 24 hours.
  8. Remove the soap from the mold and then transfer it to a cutting board. Cut the soap into bars.
  9. Place the soap bars on a container with good ventilation in order for them to cool further.

Tips:  You can also put in some scent and dried flowers to make beautiful floral soaps. You can get the All Natural Dried Flower Kits here.

How to Make Soap with Coconut Oil


Another way to make lye soap is with coconut oil, an edible type of oil extracted from the meat of mature coconuts.

Coconut oil can be beneficial as it can be used in hair products like hair masks or hot oil treatment and it also has antioxidant properties that make it great for the skin, especially for anti-wrinkles.

Making lye soap with coconut oil is recommended for vegans and vegetarians since it does not make use of animal fat.


– Coconut oil

– Lye

– Water

– Essential oils (optional)

Again, use a lye calculator in order to determine the specific amount for each ingredient.


1. Weigh your ingredients and set your crock pot to low heat.

2. Add water to a glass or ceramic bowl. Add lye to the water while mixing gently. Let the mixture cool for five to ten minutes before moving on to the next step.

3. Place the coconut oil in a pan and then heat it to 120 – 130 F. Once melted, transfer the coconut oil into the crock pot and set it to low heat. Add the lye to the crock pot and stir it a few times. Be careful not to splash the mixture into the pot.

4. Use the stick blender to mix. The mixture should end up having a texture and thickness similar to that of a light pudding.

5. Cover the pot and let it cook on low heat. The cooking time will vary according to the heat of your crock pot, so check it every now and then.

6. You would know that the soap is ready when it looks like semi-translucent Vaseline.

7. If you’re adding essential oils, make sure to wait until the mixture cools down before putting the fragrance.

8. Using a spoon, transfer the mixture into your mold and let it cool. You can put it in the fridge in order to make it cool more quickly.9. As compared to lye soap with lard, the coconut oil makes the soap harden faster and it would be more difficult to cut if the soap was made to cool for too long. Once the soap is cool and dry, cut it into bars as soon as possible.

10. Place the soap bars on a tray with good ventilation and allow them to cool and harden for a few more weeks in order for their conditioning properties to fully develop.

Want more soap recipe using lye? Try this DIY Avocado Soap with Argan Oil and Shea Butter.

Where to Buy Lye


Lye or sodium hydroxide can be bought in any hardware store or even in online stores. They are very accessible and inexpensive, that is why making your own lye soaps is easy and fun to make.

You can also turn your passion of making Soap with lye into a profitable business, why not sell your creation at a local craft fair? Check out our Top 9 Tips to Increase your Profit at a Craft Fair.

Can I Make Lye from Scratch?


Yes, of course, you can! Lye can be formed from three different sources: salt, baking soda, or wooden ashes. Listed below are processes on how to make lye from these products.


Equipment Needed:

– Flashlight battery

– Glass cup

– 20 inches of copper wire

– 1 tablespoon of salt

– A piece of cardboard


1. Combine salt and water in a glass and stir until the salt is dissolved.

2. Poke two wires through the cardboard and then attach the wires to the top of the glass with 5cm into the water-salt mixture. Make sure that the cardboard covers just a small portion of the glass in order to allow proper ventilation. Attach one of the wires to the positive and another to the negative side of the battery.

3. Bubbles will start to appear on the wire tips. Leave the wire tips in the glass until no more bubbles are observed.

4. Extract the lye (sodium hydroxide) by boiling the water at exactly 100 degrees Celsius.

5. Store the lye in a chemical container. Make sure to use gloves while doing this because lye can irritate your skin.

Baking Soda


Making lye from baking soda is easier than making it from salt or wooden ashes. All you need to do is to put the baking soda on a stove and heat it up.

Keep mixing the baking soda in order for it to cook faster. This process of heating up the baking soda (sodium bicarbonate) makes it convert into washing soda (sodium carbonate).

Once little bubbles are forming in the baking soda, it is a sign that a chemical reaction is happening. The washing soda will be ready when it is no longer bubbling or reacting.

Another way to know is if the powder is not yet ready is if it sticks to the spoon you are using to mix. Usually, baking powder sticks more than washing soda does.

Next, dissolve the washing soda into a glass of water. This creates sodium hydroxide (lye) and carbonic acid. The carbonic acid will dissolve once you boil the solution and leaves the lye behind.

Wooden Ashes


You can make lye when you mix wood ashes with water. Potassium carbonate is found on wood ash.


– Bucket (Don’t use a bucket made from aluminum.)

– Mixing spoon (Preferably wooden spoon)

– Wood ash

– Flour sifter

– water

– Used T-shirt

– Pot

– Pan


  1. Separate the white ash from the black chunks of wood that contain carbon. Sift the white ash from the chunks into a bucket.
  2. Once the sifted ash is in the bucket, use a watering can to pour the distilled water onto the ash. Make sure to wear safety goggles and gloves while doing the next steps.

Ask help from another person to stir the mixture while you our water. Continue mixing until you reach milkshake-like consistency. Let the mixture sit for about four hours.

3. Pour the mixture into a cooking pot and put the remaining sediments into an old t-shirt. Squeeze the liquid from the t-shirt into the pan and then bring the liquid to a boil.

4. Once the liquid starts boiling, take the mixture off the heat and let it sit again.

5. Pour the solution into a frying pan. Make sure to not pour any remaining sediments into the pan.

6. Simmer the solution until you start seeing bubbles. Once bubbles start to form, turn the pan into low heat and stir with a spoon until it starts to thicken. The result is a crystalline lye, a fine powder that looks like this:

There you have it! Didn’t think you can make lye with salt, baking soda, and wooden ashes, huh? If you want more DIY solutions, click here!

Disadvantages of Lye


As mentioned earlier, lye is an all-around useful product – it can be for food preservation and cleaning purposes, and a lot more. However, we should be more careful when handling lye.

Lye is a caustic substance, meaning it can be able to burn or corrode organic tissue by chemical action.

Lye is toxic. It should not be consumed or swallowed. Lye can cause chemical burns when it comes in contact with skin and can even cause blindness if it comes in contact with your eyes. It is also explosive when combined with metals such as magnesium, tin, aluminum, and zinc.

Lastly, do not mix lye with sugar. It will produce carbon monoxide which is a type of gas that is very harmful to humans when inhaled.

Given these disadvantages of lye, it is important to remember and follow the safety tips that come with handling lye.



Lye soap is easy to make because of the easy and accessible ingredients: water, lye, and oils.

Lye soap is safe to use, even for pregnant women and for those who have acne problems. It is because it contains natural ingredients like lard or coconut oil.

Just make sure to follow the safety precautions in handling lye. How to make soap that’s safe? Use a lye calculator.

Although you can buy lye from hardware stores or online shops, you can also make lye from scratch. You can make lye with salt, wooden ashes, or baking soda.

Did you like the article about the remarkable background of lye? Please let us know by putting comments or even pictures of your DIY lye soap in the comment box below! Bookmark our page to keep yourself updated or sign up for our newsletters for a chance to win a giveaway!

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