Q: How can you calculate the SAP value of cooking oil and Vegetable cooking oil? or there is a rule of thumb in determining how much lye to use? Are these oils good for the skin in general?

A: No, you cannot calculate the SAP value for either vegetable shortening or generic cooking oil because the ratios of different oils in the cooking and vegetable oils vary based on the brand.

No, there is no general rule of thumb for determining lye amounts. You must figure out lye amounts based on the specific recipe you are using. Here is a good online lye calculator.

Unfortunately, vegetable shortening oil and generic cooking oil generally are not considered the best for skin. You’ll want to stick with tried and true, single oils, such as Olive, Hazelnut or Sweet Almond Oil