Our saponification values have been gathered primarily from our suppliers and product documentation. In some cases, we have relied upon outside sources. Certain SAP values will differ from those listed in other sources because SAP values can fall within a range of values acceptable for an oil/butter/lipid. The actual value will change depending on the origin of the lipid and what the weather conditions were for that particular plant material and processing techniques. In most cases we used an average of the range so that your soap will not come out lye heavy in the event that the actual SAP value was on the lower end of the range.
These numbers are actual SAP values expressed in the number of mg of KOH required to saponify 1 g of oil/fat. When reading a certificate of analysis of an oil/fat, the SAP Value will be listed in this way.
Most soapers prefer to convert these numbers when making soap to be able to calculate their lye easily. You will see these converted values listed as decimal values. They are derived from the actual SAP value and are not true SAP values.
Dividing the SAP value by 1000 gives us a ratio of KOH to Oil in the same units (mg), and therefore becomes the ratio of KOH needed for any unit, as long as you use the same units to measure your KOH and Oils. Example: An oil with an average SAP value of 190 will require 190/1000 = 0.190 g of KOH per g of oil, or 0.190 ounces of KOH per ounce of oil, or 0.190 pounds of KOH per pound of oil.
Dividing the SAP value by 1402.50 or multiplying the KOH ratio by 40/56.1 (the ratio of the molecular weights of NaOH/KOH), gives us the amount of NaOH required for any unit, as long as you use the same units to measure your NaOH and Oils. Example: An oil with an average SAP value of 190 will require 190/1402.50 = 0.135 g of NaOH per 1 g of oil, 0.135 ounces NaOH per ounce of oil, or 0.135 pounds of NaOH per pound of oil.
To convert actual SAP Values into converted values ready to work with in any unit:
- Solid Soap (NaOH): Divide the average SAP Value by 1402.50
- Liquid Soap (KOH): Divide the average SAP Value by 1000