Find some eggshells, crush them, put them in a cup, pour some water and shake them for a few minutes, put them down for 6-8 hours, then pour them out and rinse them with water several times.

If you don't clean the scale for a long time, it will easily become a hotbed of bacteria, so the cup should be cleaned regularly, otherwise it may rust (it depends on what kind of cup you use, and the time and reason for rust are different for different cups). If you use a cup such as a magnetized cup, don't scrub it with a hard object such as a cleaning ball, which will destroy the protective layer on the surface and backfire.

It is best to use glass, which is easy to clean and does not rust.

disadvantaged

Fragile.

O(∩_∩)o ... haha laughed