“Modifying existing recipes with different oils and extracts will give you the confidence to use common guidelines and oil properties to create your soap from scratch. The general rule of thumb is to replace oils with similar oils; that is, replace solid oils with other solids, and liquid oils with other liquids. For example, olive oil is a good substitute for canola oil, but cocoa butter is not. Read chapter 5​➔​ to learn about usage rates for individual oils.”