The problem with cleaning any clear glass object, including glass jars, is preventing water spots and fog from forming due to hard water. Glass items must be cleaned with very hot water and dried immediately to ensure they look as clean as they are. There are a few other methods tested over the years that also work to make your glass crystal clear.
Wash your glass jars with dish soap and water. Immerse your jars in the soapy water and wash with a washcloth. If your jars have attached lids, make sure to clean those well too.
Apply toothpaste to the glass jar and scrub it with a toothbrush. Rinse the jar well and dry it with a towel. The toothpaste leaves the glass jar shiny and clear.
Make a paste out of baking soda and water and use a toothbrush to scrub the glass jar. Rinse well with hot water and dry with a towel. Baking soda paste works great for removing stains from glass.
Remove water spots and calcium stains by washing your glass jars in vinegar. Pour straight vinegar into a small bowl. Use a sponge dipped into the vinegar to clean the jars. Rinse well with water. You can also soak the glass jars in a white vinegar and water solution.
Clean your glass jars in the dishwasher and use a drying agent to prevent water buildup from forming. Do not use the drying feature. Allow the water to drip off the glass jars instead.