How To Free a Stuck Cork-Stopper-Lid From a Jar

How to remove a stuck cork stopper from a jar
(4 min. Read)

Sometimes cork lids get stuck in glass jars or bottles, more often than not, this happens when a strong vacuum has built up inside the glass container. Don't worry: if it got stuck, it can get un-stuck again! 

Something similar happened to one of our customers, Brandy. In her case, the jar had been a bit too close to a slow-cooking crockpot for several hours one day.

When she tried to open the jars later that evening, one of the lids was all but impossible to open up. Understandably at a loss, Brandy emailed the team at Wondrwood explaining what had happened, and asked if we had any advice.

Glass Jars with Cork Sphere Lid - How To Free A Stuck Cork Stopper Lid
How Does This Happen?

Usually, a vacuum forms inside a glass jar or bottle when there is an air-tight seal and the temperature of the air inside rapidly changes.

You may have noticed this happening when you try to open a freezer door more than once within the span of a few minutes. It opens eventually, but it definitely takes a good-bit more force the second and third time around if there's a strong vacuum. 

In Brandy's case, the temperature inside the jar had most likely reached considerably more than that of the air surrounding the jar. This would have begun to form a vacuum, making the lid seem practically impossible to remove.

    Cork stopper kitchen glass food jars
    What Did She Do?

    There are many ways to remove a stuck cork stopper from a glass jar. If the cork has become stuck due to a vacuum, you essentially want to break that vacuum. That's what Brandy did, and that's exactly what you can do too. (If you want to, no one's saying you have to do anything..)

    The two easiest ways to do this are:

    1. Change the temperature of the cork lid or the air inside the jar.

    2. Insert something small (like a toothpick or pin) between the the cork and the glass to physically break the seal - this will allow air to escape and the pressure to be released.   

    Round Cork-Lid Glass Jars


    How Should I Do That? 

    Don't worry, it's all much less complicated than it sounds. Here's all you need to do:

    Freeze & Heat*

    • Try putting the jar or bottle in the fridge or freezer* for 30 minutes or so, and then remove it to attempt removing the lid.
      • Ideally, if you can warm the glass and cool the cork lid, that would be the best option. The cork lid will react faster to heat expansion/compression than the glass, but it helps to do both at the same time.
      • To do both at the same time, you can do exactly what Brandy did: ''we tried my boyfriend’s idea to put the lid in some ice-water then run warm water around the lip of the jar.''
    * Please ensure that the glass is borosilicate - or another type of glass that's able to withstand rapid high and low temperature changes.* 

     Borosilicate glass jars | heat-proof and freezer-proof glass

    Breaking The Seal: 

    1: Grab a toothpick or a knitting needle. Using slow and steady pressure (please be careful) pry it in-between the cork lid and the jar or bottle, perhaps two or more toothpicks might be needed to fully free the lid. Don't worry about marking the cork lid, cork tends to bounce back into shape very well.  

    2: Use your grip to roll or twist the lid. This might be a little more difficult, but if you can twist or roll the cork lid, that should also break the seal. Grip the lid firmly with your thumb and first two fingers, and try to twist while pulling slightly - as if unscrewing the cork lid.

    The Deadly (Good) Combo:

    In the words of Brandy, "we tried the toothpick idea and that seemed to make it squeak, so we knew air was moving. Next we tried my boyfriend’s idea to put the lid in some ice-water then run warm water around the lip of the jar. That worked!" - What a duo. They say team work makes the dreamwork...

    How to open a glass jar with a stuck cork lid
    How Can You Prevent This From Happening Again?

    To date, here at Wondrwood, we've only heard of this ever happening to two of our customers - that's in 3 years, thousands of people - so it's very uncommon, but that doesn't mean it can't still happen to you.

    There are a few simple "best practices" that you can do to lower the odds even further of it happening, they are:

    • Try to avoid leaving your jars in a spot where it will get several hours of direct sunlight per day - this is always best to avoid for any jars with any sort of food inside.
    • Try to avoid completely sealing the cork lids while the contents of the jars are still steaming or boiling hot. As the air inside cools to room temperature again, it will cause a vacuum if the temperature-drop is significant enough.
    • Always keep your jars at a safe distance from the cooker or any other heat sources while they are sealed shut and have cork stopper style lids. 30cm or more from the heat source should be perfectly fine for most situations (please use your own judgement).
    • If you happen to forget, or bypass the tips above, just be sure to keep some toothpicks nearby in case the vacuum gets too strong! ;) 
    Want No More Stuck Lids? 

    There is one very simple solution (among others), go with screw-tops.

     Acacia Wood Screw-Topped Borosilicate Glass Jars

    1 comment

    • Alice


      Thanks for writing such an informative blog which will surely be a great help for the readers.

      I’m interested in reading your article, and your content is on point. Well done to the team.

      Either way, keep up the awesome work!

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