Quickly check the shell
Fill it with boiling water, cover tightly, and let it sit for 3-5 minutes.
The outside of the cup is cool,vacuum is not an issue.
The cup is hot on the outside,It is leaking and not keeping the temperature, so it needs to be replaced.
Measure water temperature (room temperature 25℃)
If the water temperature is ≥55℃ after 12 hours,the insulation is qualified.
It cools down to below 45℃ in 12 hours, insulation failure.
Note
If it suddenly stops keeping warm after being dropped, it means it’s broken and cannot be repaired; for wide-mouth cups and cups that have not been preheated, rapid cooling is normal.
