With a lot of use, kettles, both glass and metal, will build up mineral deposits known as scales. While you can purchase chemicals that will remove these scales, you can easily descale kettles using common kitchen ingredients for a fraction of the cost. Descaling a kitchen kettle takes only a few minutes of your time, and it will restore the kettle like new.
Fill the kettle 1/4 full of white vinegar.
Add an equal amount of water to the kettle.
Set the kettle on the stove and bring to a boil over medium-high heat. If the kettle is electric, turn it on and allow the kettle to go through its brew cycle.
Let the vinegar mixture boil for one minute. Turn of the heat. Allow the kettle to remain on the stove overnight. If it's electric, leave the vinegar water in the kettle overnight.
Drain the vinegar water from the kettle. Rinse with cool, clear water.
You can substitute a 1/4 cup of lemon juice for the vinegar if needed. If the kettle has a heavy build-up of mineral deposits, you may have to repeat this a second time. Three tablespoons of baking soda can be added to a full pot of water if cleaning a coffee maker with a glass carafe.