Ammonia cuts through soap scum and removes it from the surface of glass. Dilute 1 tbsp. of ammonia with 1 gallon of hot water in a bucket. Dampen a washcloth or sponge in the ammonia solution and wipe the glass surface. You can also combine one part of ammonia with two parts of water in a spray bottle and apply the solution direction to the soap scum areas. After you apply the ammonia solution, rinse it off with clean water.
White distilled vinegar effectively dissolves soap scum within a few minutes. Before you apply the vinegar to a shower, run the hot water for one to two minutes to help loosen the soap scum. Fill a spray bottle with vinegar or soak a non-abrasive sponge in it. Wipe down the surface and let the white vinegar rest for two to three minutes before wiping it off with a dry washcloth. You do not need to rinse white vinegar off but you can if desired.
The acid in lemon juice removes soap scum buildup as well as mineral deposits. Squeeze the juice from fresh lemons or use bottled lemon juice on the glass. Pour or spray the lemon juice directly onto the soap scum, but do not rinse it away immediately. Let the lemon juice sit for 30 minutes to 1 hour and then rinse the area with clean water. The soap scum vanishes as you rinse the area.
If all other methods prove ineffective or if you wish to make you own cleaner, use the following recipe. Pour 6 cups of cold water into a large spray bottle and then add 1/2 cup of baking soda, 1/3 cup ammonia and 1/4 cup of white distilled vinegar. After you combine all the ingredients in the bottle, shake it so that they mix well. Spray the solution onto the soap scum and scrub with a nonabrasive sponge. Never combine bleach with this solution because it can result in lethal fumes.