MODEL RELEASED. Student making soap in the laboratory from vegetable oil and sodium hydroxide (NaOH). Soap can be made from most oils or fats. Fatty acids (glyceryl esters) in the oil are hydrolised by the alkali NaOH to form alcohol and a carboxylic acid sodium salt. The soap is precipitated from solution by the addition of sodium chloride (NaCl). After manufacture most commercial soaps are treated with perfumes and colourants to improve their appearance.