How do I Convert the Oil Molecules in the Lye Soap-Making Process?
Soap is made when oils, water and lye are mixed together. Soap is the result of the chemical reaction between fats or oils and lye. Chemically, acids and bases neutralize each other and result in a salt; therefore, soap is a salt. Lye is the base and fats and oils are the acids in soap recipes. The chemical process of mixing them to make soap is called "saponification". During saponification, the oil molecules are converted in the lye soap-making process.
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Things You'll Need
- Lye
- Water
- Fats or oils
- Stove
- Pots
- Wooden spoons
- Plastic jugs
- Kitchen scale
- Kitchen thermometer
- Large soap mold
- Old towel
Instructions
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Start with a recipe for soap. Recipes are easily found in books by master soap makers such as the two referenced below. Gather the correct amount of fats or oils and lye called for in the recipe.
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Place a plastic jug on the kitchen scale and pour the correct amount of cold water into the jug. Do the same with another jug and the lye. Gently pour the water into the lye and mix carefully with a wooden spoon. The liquid will become extremely hot; either set aside or place the plastic jug in a cold water bath to cool.
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3
Pour the types and amounts of fats or oils into the kitchen pot as called for in the recipe. Heat the fats and oils to about 100 degrees F. At that point, turn the stove to simmer. Measure the temperature with a kitchen or candy thermometer. Use the same thermometer to take the temperature of the lye solution. When both the fats and lye are 100 degrees F, gently pour the lye solution into the cooking pot and stir gently with wooden spoon.
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When the mixture starts to show trailings, pour it into the soap mold. Trailings are happening when you drip some of the mixture with the spoon and they take a second to reabsorb into the pot of liquid. So, you can see trailings for a moment on top of the liquid mixture. Trailings may take anywhere from 20 minutes to an hour of gentle stirring to show; if you have stirred for an hour and don't think you see them yet, proceed anyway.
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Pour the mixture into a large soap mold. Cover and wrap in a towel. Uncover and look at the solidifying mixture once per day; some recipes will require more stirring in the mold. Stir with a wooden spoon if there is liquid on top. Over the course of two weeks, the lye will convert the oil molecules and you will have soap.
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Determine the saponification value (SAP value) of different fats and oils to create your own soap recipes. For example, the SAP value of olive oil is 189.7. Therefore, 189.7 mg of lye are required to sopanify one gram of olive oil. Use the calculator in Resources to determine appropriate amounts of lye for different types of fats and oils.
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Tips & Warnings
Keep all soap making supplies separate from other kitchen supplies.
Lye is caustic and must be treated with care. Wear gloves and safety goggles when working with lye.
References
Resources
- Photo Credit soap image by joanna wnuk from Fotolia.com
