Open a Stuck Jar With a Knife





Introduction: Open a Stuck Jar With a Knife

About: I like to make things for the internets. I also sell a pretty cool calendar at You'll like it.

Jars can be troublesome little jerks. They're stuck tight and you're stuck trying to pry them open with your hands.

To make them easier to open all you need is a regular table knife. No fancy tool, no extra junk to fill up your kitchen, just a few hits with a knife.

For those who want TWO ways to open a jar with a knife, here's part 2.

Step 1: A Few Whacks

To loosen the jar is just a matter of three or four hits on the lid with a knife so you get some dents. These dents loosen the seal and make the jar easier to open.

To be more precise, do this:

  1. Hold the back of the knife against the jar at a 45 degree angle
  2. Pull it back a bit
  3. Whack the back of the knife hard against the corner of the lid so it leaves a small dent
  4. Repeat 2-3 times around the lid
  5. Open

Step 2: What Success Looks Like

In case you're wondering just how big of a dent is appropriate, here's a close up shot. You should be able to catch your fingernail in it.

Jars can take a pretty strong hit. I've never had a jar break while doing this and I've done it hundreds of times. Check out the video in the intro to see how much abuse a salsa jar can take.



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    i made the exact same instructable! great idea! ;)

    Does this technique work on plastic jars and lids too?

    I was taught this way over 50 years ago by my grandmother. back then men were at work while women stayed home to open jars.

    5 replies

    True story... my grandmoter was a professional jar opener. She was hired by IBM in the 30's. back then, IBM produced peanuts for elephants who were the country's main form of public transportation. The company would import hundreds of peanut butter jars from Amsterdam and my grandmother would spend all day opening the jars and handing them off to the Peanut Assembler, who would reassemble the peanuts for packaging. In 1934, my grandmother was invited to England to meet the queen, as she (my grandmother) had opened her 5 millionth jar. In 1940, my grandmother lost her job as the country abandonded elephant transportation in favor of porcupines... and, as we all know, porkupines don't like peanuts.

    I would like to hang out with you. More stories please!

    how does one reassemble peanuts from peanut butter?

    lol, sounds more like empty peanut butter jars?

    This seems a little far fetched but because I didn't know your grandmother I'm going to take your word for it ;)

    Despite the many alternatives presented, whacking the jar with a knife, as shown, is by far the simplest/fastest. I have been doing this for 50 years with never a problem.

    What works even better , using the same knife, slide the tip end between the glass and the lid, and turn the knife slightly, this will break the vacuum seal, then it's a breeze to open from there. Doesn't dent the lid either.

    7 replies

    You're absolutely right! Hitting the lid with the knife can crack or dent the glass border, so pieces of glass can enter the food... Breaking the seal or loosen the lid from dried food is easily accomplished the way you explained. As an added bonus, the same method (knife between lid and glass) works for oppening beer or soda bottles without the risk of breaking something.

    I have been using your method for years but with a vintage 60s beer can opener to pry with. I never have broken a jar top. Sometimes rusted fruit jar bands are so hard to loosen the bands are unuseable after getting them off.

    This is the way I always open new jarred products. The goal is to pop the seal, not rip the top off. I will admit that sometimes I am a bit worried about tiny pieces of glass breaking off, but so far, no cut lips. Oh, and definitely use a metal knife, preferably stainless steel or some other hardness.

    I haven't tried that in a long time and when I did it was with a pretty flimsy knife. So... that must've been a college dorm. As I recall, the knife end got twisted and the jar didn't open. Probably works better with a "real" knife.

    so maybe try the spoon, the distance between hand and top of the spoon is less

    most butter knives are strong enough. You really need to get the point up inside the lid. You basically are lifting the lid just so slightly to allow air in. probabally the blunter the point, the better - it will give more area, whereas a pointed end knife will tend to twist more.

    OK, I went back to the market and got two more jars to try that out. One worked great. The other not so much. So maybe just keep both in mind.

    Thanks for the tip, here are the results.