Ammonia, soda, sodium, and potassium hydroxide are the main ingredients for dirt-dissolving alkalis, which are able to remove particularly stubborn grease and oil-based deposits (e.g. in the oven) and obstructions (e.g. in the drain). However, alkalis are unable to dissolve lime. Cleaners which mainly consist of strong bases are corrosive. The hazard labels and safety notices must be precisely observed.