Hi I’m joining your club! I have 40 old jars, a 2007 presto pressure canner, & the 38th ed. ball blue book started right now! My beginner questions – some of my jars have manufacturer defects, can they be pressure canned? If my jar has no embossed label, how do I know if it is a safe canning jar?
by purpledreamer1622
4 Comments
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Don’t use any jars with defects for canning. Heat +defects=exploding glass. The temperature changes make it even more likely, it could explode while your holding it.
Not all jars are embossed, and some jars that are embossed are not safe (some commercial pasta sauce jars are like this). The rim of the jar is what matters, it needs to be of a standard size (quart, pint, and half pint are most common) and it needs to use a 2 peice lid set up. It can be either regular mouth or wide mouth.
Don’t forget to remove your lid rings after fully cooling!
What do you mean by manufacturer defect, anything other than lacking the raised branding?
I would probably not trust anything that doesn’t have obvious branding; there may be hints somewhere on the jar that would let some of the old hands identify it, but I would be concerned that these are things like re-purposed commercial jars that aren’t suitable for canning. Some of the issues there include slight differences in opening size or rim geometry that can affect the quality of the seal, slightly wrong thread that won’t properly hold the ring in place, or thinner glass that’s not going to hold up to the canning process (e.g. may explode in the canner).
If they were more recent vintage I’d be worried that they were part of the recent trend for using “Mason” jars for everything except canning. I recently found several jars in my collection that turned out to have been given out as party favours full of candy from children’s birthday parties. One had a layer of plastic applied to the outside (melted off under hot tap water), and another shattered with a quick tap of a spoon on the outside.
Kerr, Ball, Golden Harvest and Bernardin are the main players in North America. There were a couple of GEM jar companies but they are no longer in production and lids are hard to find. Overseas there appears to be less choice…Weck from Germany, Kilner from the UK and Quattro Stagioni from Italy mention canning applications but I’m not sure how they compare to Ball brands.
I would be wary of jars that have zero info embossed on them, usually they are old mayo jars (or some other commercial product).
You can always post pictures here and someone can tell you if it’s a proper canning jar. Really old jars can have small bubbles and other inclusions…sometimes it’s perfectly okay. Others may look fine but have tiny knicks from metal knives scraping inside which may break during the canning process.