If you want to save money on home canning, one of the first things you will probably do is to try and find used canning jars. People who are just getting started with home canning may be put off by the price of new jars, so used jars can be a great alternative. However, used jars vary in quality, and good quality jars are necessary for canning food safely.
Check for cracks
When you find used jars, always look to see if there are cracks near the bottom or at the bottom of the jars.
Cracks can be caused by exposure to extreme temperatures. For example, if a jar was cold and boiling water was poured into it, it may have cracked. Cracks are not always easy to see; take your time in examining the sides and the rim for any hairline cracks. Even these very thin cracks will make the jar unusable for canning.
Use clean jars
Check to make sure that the jar is relatively clean. A jar may have been used to store various things, or it may have been sitting in someone’s shed or garage for years without proper cleaning. If you find a jar that’s caked in dirt, it will be difficult to see if it has cracks, if the rim is still intact, or if it has pitting. However, clean jars don’t always mean that they’re in perfect condition, so inspect all jars thoroughly, regardless of their cleanliness.
Inspect the rims
Look at a new jar and compare it to the used ones that you are considering. How does the old jar’s rim compare? Does the old jar have any stains that you may not be able to remove? Do you see any rust? If the used jar’s rim is cracked or broken in any way, you will not be able to screw a band on or place a lid on it or use it for canning, though it might make an inexpensive vase. If the used jar has stains that can’t be removed with dishwashing liquid, you may consider them too much work for their use.
If possible, ask the owner of the jars where they have been stored and what they have been used for. It would be useful to know if they were exposed to the elements or sitting in an attic, if they were used for canning, or if they weren’t used at all. The best “used” jars, however, are the ones that a previous owner purchased new but never actually used.
You can get a good deal on used canning jars, but it’s important that they’re good quality and safe for canning.