To use glass preserving jars for canning involves obeying specific rules. You should not bend them - unless you have tested alternatives that work. Again, there are limits to how you can use large canning jars.
So, which sizes of large canning jars are the best? Or what traits should they have to ensure their longevity? Yet again, be wary of anything that can affect the glass quality. We will embark on how to select and use/reuse large canning jars below.
Features of Canning Jars
Glass preserving jars are safe to reuse within 10 to 13 years. Again, for each food recipe or processing method, the size matters. You should not choose an arbitrary size, or one too big or too small for a recipe. This will affect the outcome of your cooking in a serious way.
Five factors affect the usefulness and longevity of glass preserving jars:
- The jars’s capacity/volume
- The jar’s mouth and shoulder type
- The width of the jar itself
- The thickness of the glass wall
- The jar’s colour
Let's do a quick check on the types of glass preserving jars. Note that:
- 1 gallon = 128 fluid ounces
= 4 quarts
= 8 pints
(US measurement)
Capacity/Volume
To avoid quick cracking or breakage, consider the weight and size of a canning jar. The larger a glass jar, the longer it takes to cook food in it. And heat reaches the core of the food slower than the outermost parts. Which means the food at the core may undercook in a large jar.
Mouth Size
In terms of the mouth size, there are two broad types of glass preserving jars. These are wide-mouthed and regular-mouthed glass jars.
Wide-mouthed glass jars have parallel/straight or V-shaped sides. They are good for canning foods that need plenty of space. That includes extra headspace to accommodate expansion while boiling or freezing them. As such, they are suitable for foods with high fluid content. Whole or large chunks of fruits and veggies can fit into them without problems. Use them for sauces, pickled foods, soups, stews, stocks, and juices.
While regular-mouthed glass jars have shoulders that slant or curve inwards. They are convenient for keeping pourable foods - like soups, sauces, or jellies. And for small pieces of veggies and fruits. They are ideal for dried foods, or foods with little water content. But if you will freeze the food later on, avoid using regular-mouthed jars. While freezing, the expansion of food affects the curved-in shoulder. This can cause cracks or breakage.
Width of the Jar
Narrow glass jars are not good for canning. They are weaker at handling extreme temperatures than wider jars. Because narrow glass jars are less able to handle the expansion of food.
Thickness of the Glass Wall
The recommended glass jars for canning should be thick-walled, tempered glass. It is advisable to purchase and reuse designated canning jars. Commercially-produced jars for food packaging are often not thick enough. They cannot withstand the high pressure and temperature of canning. As such, avoid canning with store-bought glass jars of salad dressing or mayonnaise.
The Do's and Don'ts of Reusing Large Canning Jars
We can classify canning jars of 32-ounce size and above as large canning jars. Large canning jars are more prone to damage with every movement and reuse. However, 32-ounce and 64-ounce canning jars are quite versatile. They can keep sauces, soups, and canned or pickled vegetables and fruits.
To enjoy reusing large canning jars, abide by the rules below:
- Actively-used canning jars should be 32 ounces and below, at best.
- Use bigger jars for food storage. Like baking supplies, dry grains, fresh milk, beverages, and acidic juices.
- Always check the condition of a canning jar before usage. Dispose of those with any noticeable crack, fissure, or nick.
- Do not expose glass jars to sudden temperature changes - referred to as ‘thermal shock’. For instance, anything hot should not go straight into a cold canning jar. Neither should anything cold go straight into a heated canning jar. Warm the jars up until you pour hot food/drink inside them. Do the opposite for cold food/drink. Leave heated or frozen canning jars to cool down or thaw at room temperature.
- Whatever the size, glass jars must be very clean before using them for canning. Use a dishwasher for complete sterilization of large canning jars that can fit in. Otherwise, scrub them inside-out in hot water and mild soap, and rinse them well. Then sterilize them in a boiling water bath for 10 minutes at most. Or do a vinegar/alcohol rinse.
- The best lids for canning are replaceable two-piece lids. For each canning, it is advisable to use new lids. But you can reuse the ring bands they came with - those in good shape. Modern canning lids no longer need boiling. Nevertheless, clean both the ring bands and the lids before using them.
- Remember to leave some headspace atop the food/drink. After filling each jar, tighten the ring band - finger-tight is enough. To create an effective seal, do not over-tighten or under-tighten the ring band. Nor readjust it. When the jars complete cooling down, clean and put away the ring bands.
- You should label each canning jar with the content and date. If 2 or more batches are available, state the batch number. It helps you to check the food and avoid spoilage.
Conclusion
Large canning jars include all canning jars of at least 32 ounces. Aside from 32-ounce and 64-ounce sizes, large canning jars work best for food storage. It is also advisable to dispose of glass preserving jars older than a decade.
The best sizes of canning jars are those of 32 ounces and lower. For any food/drink you will later freeze, can it with a wide-mouthed glass jar. Be careful to avoid thermal shock. And for best results, use new two-piece lids each time you prepare canned food/drink.