# canning jars any good?



## fencepuller (Jun 28, 2013)

I acquired boxes of canning jars, quarts and pints in good shape except there's a circular shape like crack at the bottom of all of them. The circular shape is about the size of a silver dollar. I'm afraid they have been heat stressed and will break should I use them. Has anyone had jars like these and did you use them that way?


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## simi-steading (Sep 27, 2012)

Are you sure it's a crack, and not the imprint from the mold when they were made?

If they really are cracks, they are trash...


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## Taylor R. (Apr 3, 2013)

Yep, I'd be incredibly leery to use them if they're really cracked. However, they'll give some crafter great joy even if they ARE cracked.


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## po boy (Jul 12, 2010)

What is the brand name? Are they all the same brand?


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## froebeli (Feb 14, 2012)

A picture or two would help also...


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## fencepuller (Jun 28, 2013)

The canning jars are all different brands, but they all have the same circular crack on the bottom. Here's a few pictures.


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## simi-steading (Sep 27, 2012)

That doesn't appear to be a crack.. That appears to be a seam from the molds.. at least from what I can see in the pictures..

To test the jar, wrap a string around the neck of it.. then hold it by the string and give the jar a tap with a spoon or something.. You will be able to tell if the jar is cracked or not by if it rings or sounds bad..


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## Tracy (May 2, 2002)

Can some water in them for a test.


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## simi-steading (Sep 27, 2012)

Eh.. I don't know though.. that second picture, it does look like a crack through the lettering... like the light is bouncing off the inside of the jar and not from a ridge.. 

Try seeing if they ring or not.. a cracked jar won't..


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## RuralSerenity (Jul 6, 2009)

I wonder if they are "seconds".


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## fencepuller (Jun 28, 2013)

Thanks-you for all the replies. Will try to make the glass ring when tapped. Afraid to put food in them for now.


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## PackerBacker (Jul 17, 2013)

Those aren't cracks but seams.

CAN AWAY!!!


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## o&itw (Dec 19, 2008)

PackerBacker said:


> Those aren't cracks but seams.
> 
> CAN AWAY!!!



I second that


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## PlicketyCat (Jul 14, 2010)

I agree. I doubt these are cracks, they look more like mold lines. They're just too smooth and uniform... it's highly unlikely that a whole box of jars from different manufacturers and lots would have nearly identical cracks in them like these, even if the box they were in was dropped onto a hard surface from a height or slammed hard during stacking.

However, if they are factory seconds, they might not take the stress of canning. I'd try BWB some dyed water first to see what happens. I'd be a little leary of using these for pressure canning since the blemishes may result in loss of structural integrity at pressure.


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## LWMSAVON (Oct 8, 2002)

I have a few old jars that look like that. They aren't cracks, but molding seams.


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## Horseyrider (Aug 8, 2010)

I can in those all the time, and they're fine. They were there in the jars when I bought them in 1979, and they're still working, year after year.

Can away!!!


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## 349141 (Oct 16, 2012)

I grew up canning; most of my mom's canning jars had that and we never had any issues. I think it is just part of the mold when they were made.


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## denno (Nov 14, 2012)

Old subject, I guess, but I am coming upon it bigtime.
Many of my jars are "acquired."
Many of them have circular features on the bottom.
I observe two types.
1) centered, raised circles that appear to be from the mold.
2) usually-not-centered circles that may go through the letters and which I can catch a fingernail in.

I am guessing the latter are cracks. How come so ubiquitous?
One observation was that a lot of jars I put on the bottom shelf of the dishwasher came out cracked. But this could have been that I did not look as closely when I put them in, or that the cleaned jars were easier to examine.

I don't seem to be seeing the pix posted earlier.
This ain't definitive. Comments welcome.


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## where I want to (Oct 28, 2008)

Really old canning jars may have Pontil marks. Later ones had plain mold marks. But in all of my varied aged canning jars, none had circular cracks on the bottom. Any cracks seemed to go over the rounded part too so I can't think there would be many with that particular crack.

That's Pontil not pontiac. I hate auto correct- it refuses to let me start Pontil without a capitalization.


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## po boy (Jul 12, 2010)

denno said:


> Old subject, I guess, but I am coming upon it bigtime.
> Many of my jars are "acquired."
> Many of them have circular features on the bottom.
> I observe two types.
> ...


Several years ago my 94 year old Neighbor passed away and I acquired some canning jars from the estate sale. There was a wide assortment of jars, some were one and a half pint jars that appeared to be real canning jars. Some of those failed when I used them. Looked like the bottoms just came off in a perfect circle.


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## simi-steading (Sep 27, 2012)

Be careful about using a knife to remove bubbles from the side of a jar. You really don't want to use metal. A metal knife can scratch the jar, especially along the bottom, and this can cause the bottom of the jar to break and fall out.

Not any different than using a glass cutter to make a score.


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## Use Less (Nov 8, 2007)

I have had a few jars where the entire bottom and up perhaps a 1/2" came off when trying to clean. I think they may have frozen with food in them.


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## Ozarks Tom (May 27, 2011)

On older jars, someone might at one time have canned putting them directly on the bottom of the canner rather than on a rack/spacer disc. This can cause the bottoms to crack.


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