It was my first try to canning tomato sauce but I failed.

  • I prepared a tomato pizza sauce.
  • I boiled a jar and lid then removed it
  • I filled the jar with sauce and left one inch empty space and closed with the lid.
  • Then I put it in the boiling water and what happened:

    • As soon as I put the jar in the hot boiling water, some air bubbles appeared.
    • Then after few seconds, the jar broke from its bottom

And I failed in my first experiment.

What should I be doing differently for this not to happen next time?

  • 1
    Was it a canning jar? Was the tomato sauce hot or cold? Was the jar sitting on the bottom of a pot or suspended in a canning rack? Commented Jun 9, 2013 at 13:07

3 Answers 3


Jars burst either because of internal pressure or thermal shock.

There are a couple things you can do to reduce the risk of bursting.

  • use actual canning jars.
    Some people like to reuse regular jars that aren't as strong. This will often work fine but increases the risk of bursting.
  • make sure the jar is hot.
    A cold jar into hot water or a hot jar into cold water will burst almost every time.
  • bring water to a boil after adding jars
  • don't overtighten lids.
    Rings should be tightened just enough to firmly hold the lid on. Too much and pressure won't be able to escape during boiling. Remember the bottle is sealed by pressure-not by the ring.

Based on your description, if you had any of these problems I would suspect the last.
However, sometimes bottles just burst because of manufacturing defects. This doesn't happen often but it is sad when it does.

  • Thanks for your detail reply. Jar was placed directly in boiling water without canning rack. It was not in standing position but in laying position (Actually i saw in one youtube video and they was canning by laying the jars). Your answers are really logical.
    – DataMiner
    Commented Jun 9, 2013 at 14:52

Your jar may have died of thermal shock. The bottom of your canning pot should have a spacer that keeps the jars from directly touching the pot's potentially quite hot bottom. You can buy purpose-built spacing grids, or use something like this:

Those are canning jar lids

Those are canning jar lids in the bottom of the pot.

  • Can we use this type of jars, click for jars Photo ?
    – DataMiner
    Commented Jun 9, 2013 at 15:55
  • Sure. That's just an old style canning jar, unless possibly it's a modern knockoff meant soley for decorative purposes. For general and accurate canning info, check this site: nchfp.uga.edu Commented Jun 9, 2013 at 17:55
  • By the way, the purpose of boiling method is to "remove the air" from the jar? or it change some chemical properties of the sauce too?
    – DataMiner
    Commented Jun 9, 2013 at 22:28
  • 2
    Purpose is to sterilize, but it also replaces the air in the bottle w hot steam, so that when things cool down the steam condenses and you get a nice vacuum seal. Commented Jun 9, 2013 at 23:00

It seems that you added room temperature or (just warm) jars into boiling water, thermal shock broke the glass. Put room temperature closed jars in water, put cotton kitchen cloth between jars in the water, turn the gas on and continue. When the water starts boiling leave it boiling for 30 to 40 min. Turn off gas, leave them for one hour to cool and then take them out and dont open the jars. Store them in a relatively dark area, open only the one u need to use first. Basically speaking, jars with circular metal lids should have their top lid surface become slightly concave after boiling, this means the air went out and now they can be stored for a year. If the top of the lid remains straight or convex, there is a chance that the sauce will rot after a few weeks because air is still inside, and bacteria can resurrect to life.

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