How do I read soap calculator values?
Short answer
They're predictions calculated from fatty-acid profiles. Use them as a guide, not as laws.
Explanation
The book's ranges: hardness 29–54 (ideal 35–45); cleansing 12–22 (ideal 15–20, and above 22 may dry skin, so offset with more superfat); conditioning 44–69; bubbly lather 14–46; creamy lather 16–48. The iodine value measures unsaturation and rancidity risk: ideally under 60, and above 70 means a high risk of rancidity and 'dreaded orange spots'.
The numbers ignore additives, water quality and curing conditions. 100% olive Castile scores only about 17 for hardness, yet becomes very hard after a long cure.
What to do
- The book recommends SoapCalc.net.
- Always make a test batch; the numbers are a starting point.
Source: The Big Book of Homemade Soap — Interpreting Soap Calculator Quality Values