1. What is the Lye Calculation?

The lye calculation determines the amount of lye needed to saponify a given quantity of oil in soap making. It's based on the saponification (SAP) value of the oil, which indicates how much lye is required to convert the oil into soap.

2. How Does the Calculator Work?

The calculator uses the lye formula:

Where:

• \( Oil \) — Amount of oil in grams
• \( SAP \) — Saponification value in mg KOH/g

Explanation: The formula calculates the precise amount of lye needed to completely saponify the specified amount of oil, ensuring proper soap formation without excess lye.

3. Importance of Lye Calculation

Details: Accurate lye calculation is essential for producing safe, high-quality soap. Too much lye can result in harsh, caustic soap, while too little lye may leave unsaponified oil, leading to rancidity.

4. Using the Calculator

Tips: Enter the oil amount in grams and the SAP value in mg KOH/g. Both values must be positive numbers for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is SAP value?
A: SAP (Saponification) value is the amount of lye (in mg) required to saponify 1 gram of oil or fat. Different oils have different SAP values.

Q2: Why divide by 1000 in the formula?
A: The division by 1000 converts the result from milligrams to grams, providing the lye amount in the same unit as the oil measurement.

Q3: Should I use the exact calculated lye amount?
A: Many soap makers use a "lye discount" (reducing lye by 5-10%) to ensure all lye is consumed and create a milder, more moisturizing soap.

Q4: Are SAP values the same for all lye types?
A: SAP values are typically given for potassium hydroxide (KOH). For sodium hydroxide (NaOH), you need to use a conversion factor (usually multiply by 0.714).

Q5: Where can I find SAP values for different oils?
A: SAP values are available in soap making reference books, online databases, and from oil suppliers. Common oils have well-established SAP values.