How to Loosen a Jar Lid
By Stephen Bucaro
Food is stored in jars by putting the hot food in a hot jar. Then when the jar and its
contents cool down, the contents shrink, leaving a vacuum at the top of the jar. With the contents
having been heated, killing all microorganisms, and no air being in the jar, the food can last
unspoiled for a very long time. But the vacuum inside the jar makes it very difficult to remove
The best way to loosen the lid of a vacuum sealed jar is to run hot water over the jar
and lid. The hot water causes the contents of the jar to expand, reducing the vacuum pressure.
Since metal conducts heat better than glass, the hot water will also cause the lid to expand
more than the jar, causing it to loosen up.
But if you don't have hot water handy, you can loosen the lid by tapping around its circumference
with a metal object like a butter knife. This will deform the lid and weaken the seal so that
it may be removed more easily. Don't tap the lid too hard or the class jar will break, making
its contents too dangerous to consume.
Another method is to use a piece of rubber sheet material to increase the friction between
your hand and the metal lid. Although rubber is the best non-slip material, you may find that
just opening the lid while wearing cloth gloves, like a pot holder, will do the job.
Of course, if it's a real stubborn lid, you may have to use several of these methods
simultaneously. You may have to run hot water over the jar, then tap around the lid, then try
to remove it while wearing gloves.