Where Does the 20-25% Rule Come From?

​I don't know about anyone else but I was trying to find out where the 20-25% rule came from and I was not finding much. So I asked on Reddit and got an amazing answer. From Reddit on the r/diybueaty from elegantbeigemetallic “Emulsifying wax was designed to simplify the process of making emulsions with nonionic emulsifiers, so the simple percentage estimates could be used instead of having to do calculations using the HLB system.