Why Hot Water Is Effective In Opening Stuck Jars

Jan 08, 2024

Running hot water over the lid of a stubborn jar is an effective technique to loosen it up when you don't have a specialty kitchen tool to do the job. You've probably had to use this method at some point in your culinary journey when you've gone to unscrew a lid from a jar of pasta sauce for your spaghetti dinner, or a jar of sliced pickles for your copycat Chick-fil-A sandwich. But why does it work so well?

The answer is quite simple: thermal expansion. As you run the hot water over the metal lid for as little as 30 seconds, the slight rise in temperature helps the metal to expand ever so slightly — just enough to spare you the strain of twisting it open. Both the metal lid and the glass jar expand due to the heat, but the metal expands more quickly, giving you the edge you need to get it open

Dealing with a tightly sealed jar can become an unexpected challenge, testing not only your hands but perhaps also your ego when it comes time to open it. But remember, this is a universal experience. The culprit is the vacuum seal, created internally when a jar is sealed. The process starts with warm ingredients placed into the jars. Then, a lid is screwed on tightly, securing the contents until you're ready to use them. As the food cools, a tight seal is formed that keeps the food fresh and safe from bacteria.

Opening a sealed jar with hot water is a simple and effective method. How do you know when the seal has been broken? Listen for the telltale quiet pop of the lid as you give it a twist. This hot water method is safe as long as the water isn't so hot that it could burn your hands. And the real benefit? It definitely works.