To clean crusty glass, first pour half glass hot boiled water and then pour one tea spoon of citric acid. If you do not have citric acid, you can use two limes juice. Stir it, and leave it for one or two hours. After that wash the glass.
If you want to clean up crusty teapot, first pour water around half of the teapot, and add one table spoon of citric acid or three limes juice. After that boil the teapot until it boiled. Then wait until it cold. After that was the teapot. If the crust is too thick, you can repeat the process.
Have a nice try.
