The mud in the green trough contains a lot of iron, which can prevent tea for a long time, resulting in excessive precipitation of tannic acid in tea and some chemical reactions with the mud. It is estimated that a small amount of ferrous sulfate is produced, so it is acidic. This is not a problem with the pot. It is often encountered to raise a new pot with residual tea.

Suggestion: 1, after repeatedly boiling with water, fully dry it, and dry it for a period of time to reduce the amount until it disappears; 2. Remember not to raise a pot with residual tea in the future, and clean the teapot immediately after drinking tea. However, from the perspective of health preservation, tea stains on any utensils should be removed in time. Because: tea scale contains cadmium, lead, iron, arsenic, mercury and other metal substances. They are brought into the body when drinking tea, and combine with protein, fat, vitamins and other nutrients in food to produce insoluble precipitate, which hinders the absorption of nutrients. At the same time, these oxides can also cause diseases and dysfunction of nervous, digestive, urinary and hematopoietic systems, especially arsenic and cadmium can cause cancer, cause fetal malformation and endanger health. Therefore, anyone who has the habit of drinking tea should always clean up the tea dirt on the inner wall of the tea set in time to avoid its harm to health.