It differs depending on what measurement sample is adhering to it. Use a cleaning method appropriate for the sample.
If you are uncertain about the cleaning method, use the following sequence: hot water → synthetic kitchen detergent → synthetic household detergent → weak acid and alcohol. Then check the results.
If the above method is insufficient, soak it overnight in a commercially available chromic acid mixture, and then clean it.


【Caution】
Chromic acid mixtures contain toxic substances. For the handling and liquid disposal, take appropriate measures such as asking for the assistance of a relevant agency in accordance with regional laws and ordinances.