A discolored or stained glass vessel should be filled with water, pour two teaspoons of ammonia, leave it overnight, then rinse and wash.
Very stubborn stains can sometimes be removed by soaking in a caustic soda solution (half a cup of baking soda on 2 l of water). Remember to rinse the glass thoroughly after the procedure. To remove hard water marks, soak the dish in distilled water or a solution of water with vinegar.
Never try to remove stains by rubbing.
Alcohol often leaves dark marks on the glass. Carafes are the most common victims of this type of dirt, especially when stored clogged with cork.
If calcium carbonate deposits have previously formed on the cookware, stains can be very difficult to remove. Unfortunately, such stains cannot be completely removed, however, you can try to remove them with acid. To remove alcohol residue inside the vessel, you need to fill them halfway with salt vinegar, then add a quarter cup of raw rice or sand and stir intensively for a while. After rinsing thoroughly, drain the water. Dirty glass tops and shelves are cleaned with a cloth sprinkled with denatured alcohol.