How does the button on my pickle jar pop once opened for the first time?

Question

I have this button on a few jars around the house like jam jars, they are always glass. Why does the “button” pop once and never again?

In: Physics

Answer 1

the bottling process creates a lower pressure environment inside the jar that causes the air outside the jar to press the button down. once you open the jar for the first time, the air inside the jar mixes with the air outside the jar and they are equal. so unless you can seal the jar again and then lower the pressure inside the jar, it’s never going to pop again.