To clean hard water stains, we recommend using a 50/50 solution (equal parts of Calcium, Lime and Rust Remover and warm water) into a glass or porcelain bowl. Apply solution to the affected stained areas of the glasses using a damp cloth or sponge. After 2 minutes, rinse thoroughly with cold, clean water. If it seems that Calcium, Lime and Rust Remover helped a bit but the glasses are not completely clear, repeat at full strength if necessary. Due to the natural density and hardness of calcium as a mineral, the calcium can actually etch and embed itself into the material of the glass (usually present by having a cloudy appearance vs. spotty).