The term 'Harsh Cleaning Agent' can be summarized by the three-letter word 'LYE'. LYE is a highly alkaline substance, usually sodium hydroxide, that is used in a variety of cleaning and manufacturing processes. It is a powerful cleaning agent that can be used to remove dirt, grease, and other substances from surfaces. It is also used in the production of soaps, detergents, and other products. LYE is a harsh chemical and should be handled with care.