When making homemade soap it is essential to find out how much lye you need by weight. Using volume could lead to too little lye--a very oily soap--or too much lye--a harsh drying soap. You can use this calculator to determine the quality of soaps as well how much lye and liquid you will need for your soap batch. You can find the lye calculator here:
http://www.metaphysicalfarms.com/pages/Lye-Calculator.html