How to wash the mascara bottle?

Update:16-10-2020
Summary:

1. First soak in warm water, then pour in cleansing oil […]

1. First soak in warm water, then pour in cleansing oil or toner and shake vigorously, and finally rinse with water.
2. The mouth of the mascara bottle is small and the bottle is deep, so it can be cleaned with a cotton swab.
3. If you are worried that the cleansing oil will remain in the bottle, just use olive oil instead.