Lye is one of the fundamental ingredients of soap making, so it’s important to understand how to use it properly (photo courtesy of flick user maoquai).
If you enjoy this article and want to learn more about making soap at home, get instant access to our free soap making guide which covers all the basic elements of soap making, or get 10 years of soap making experience in our comprehensive Soap Making Bible with exclusive web bonuses for less than the cost of your first batch of soap.
Lye is one of the three key ingredients in the soap making process.
Lye is a caustic alkaline chemical that dissolves substances like fat, and has a high degree of reactivity with other materials.
It is also known as Sodium Hydroxide.
If you know about soap or have been learning about making soap, you might know that almost all handmade soaps are made of Sodium hydroxide except for a few liquid soaps that are made of Potassium hydroxide. Potassium hydroxide, unknown to many, is also a type of lye used to make liquid soap.
It is important to note though that potassium hydroxide and sodium hydroxide are not interchangeable in soap recipes. So to put it simply, basically all soaps are made from lye.
Lye is a very important ingredient in making soap as the hydroxide in lye binds with the fats to form soap. Lye is extremely caustic and can burn the skin.
When lye is mixed with water and oils, in a chemical process called saponification, the lye turns the fats and oils into soap.
Lye used to be made by soaking wood ashes in water, but now it is readily available at most hardware and grocery stores.
There are certain precautions which must be taken when working with lye for soap making; it is a corrosive chemical, which can cause severe damage to skin, eyes, and the respiratory system.
Also, be sure to purchase lye that is labeled for soap making, There are different uses for lye so make sure you’re getting the right one.
Always use the right equipment and wear protective clothing – long sleeves, long pants, socks and shoes, an apron, goggles and gloves – when working with lye.
Vinegar can help to neutralize lye spills, so keep some on hand.
Familiarize yourself with emergency procedures in case you get the lye mixture on your skin or in your eyes; if possible, keep a lye MSDS (material safety data sheet) on hand as a quick reference in case of emergency.
When making soap with lye, work in a well-ventilated area (preferably outside). Lye releases toxic fumes when it is mixed with water and these vapors can be severely irritating to the respiratory system.
Keep the lye in clearly-labeled containers, out of the reach of children and pets, and use the lye containers only when making soap.
All of this may sound daunting, and the truth is that lye is a dangerous chemical, but if the proper precautions are taken, you can avoid accidents and find that making lye soap by hand is a challenging and rewarding experience.
After familiarizing yourself with the proper way to handle lye, and the precautions that must be taken, you will be ready to start making your own lye soap.
Here is a very basic lye soap recipe that is perfect for beginners:
*340g of sodium hydroxide lye (NaOH)
*5 lbs. lard
*21 ½ oz. (605g) cold water
(You may wish to add some essential oils or fragrance oils to your recipe too).
*Safety equipment (see here)
*Stainless steel pot
*1-2 quart glass bowl
*1 plastic or wooden spoon
*Shallow cardboard box, lined with cellophane or trash bag
*Glass candy thermometer
*Rubber or plastic spatula
Pour the cold water into the glass bowl.
Very slowly, begin adding the lye to the water, stirring constantly. (Never add water to lye, because it will boil and splatter everywhere)
The temperature of the lye and water mixture will increase as the lye reacts with the water; once all of the lye is added to the water, let the mixture stand until it reaches about 85 degrees Fahrenheit (29 celsius).
Heat the lard gently in the stainless steel pot, stirring frequently, until it reaches about 95 degrees Fahrenheit.
Slowly pour the lye-water mixture into the melted lard, stirring constantly.
Once all of the lye is added, the mixture will begin to look creamy, and then will have the consistency of pudding.
This may take anywhere from 15-45 minutes.
You will know that the mixture has reached trace when you take a bit of the mixture on the spoon, and drizzle it across the top of the batter; if it leaves a trace, instead of mixing right back in, the mixture is ready to go into the molds.
Use the spatula to scrape the mixture out of the stainless-steel pot and into the cardboard box mold.
After 4-5 hours, the soap should be hard enough to cut into bars.
Let the bars cure for approximately one month before using the soap.
Once you master basic soap recipes, you can start adding essential or fragrance oils and natural colorants to make colored, perfumed soap that is customized to your personal tastes. You can use them yourself, or sell them, and they make great gifts.
Take the next step
Download our FREE ebook, ‘How To Make Soap At Home’, by clicking here.