Mason Canning Jars
Mason glass jars are designed to be reused. Canning jars have a life expectancy of 10 to 13 years.You will discover more breakage after that because of the wear and tear of normal use. Each time a jar is used and exposed to heat, it is subject to stress. Over time, this stress may create hairpin cracks that will weaken the glass. Jars that are handled carefully may still be in good condition and suitable for canning beyond 10 years.
Recently, an Extension Educator was asked about using old jars from the 1920s to 1970s. Jars from the earlier period should be considered antiques and used only for decorative purposes. Use them as vases or canisters. The tinted ones add a pretty touch of color to a room. Jars with wire bales or rubber rings used with glass or zinc lids should be used for storage only.
Jars from the mid-century often have a flat rim with rougher edges that sometimes cut through the sealing compound of the lid.
The glass in newer jars appears to be thinner, but it has been tempered and is stronger.
Use caution when buying used jars. In the long run, it is often more economical to purchase new jars because you are risking less cracking of jars during processing and loss of product.
If you use older jars from garage sales or jars handed down through the family. Examine the jars carefully for any nicks, cracks, or hairline stress. Examine the sealing edge for smoothness.
We are seeing several new brands of jars on store shelves. Many are imported, and we do not have any information about the quality of those jars.
Colored Glass
You may find colored jars—blue, green, and purple—made for home food preservation; the colored glass may distort the appearance of the food in the jar.Other colored jars, such as yellow ones, are designed for craft projects. Look at box labels to determine that the jars are suitable for canning. Some clear jars are made for craft purposes and are not suitable for canning. Some will have a warning "not for canning" molded into the glass.
Decorative Jars
Ball released newly designed jars in a spiral shape in 16 and 28-ounce sizes, and a Sharing Mason Jar (6-sided) is available in a 16-ounce size. This year, they introduced a stackable jar.Some popular European Jars also come in different sizes and shapes.Tulip-shaped jars are not recommended because the wider part of the jar will not heat at the same rate as the more narrow part.
Sizes of Jars
Directions for heat processing are based on the size of the jar.
- Most fruit and vegetable directions include times and pressures for pint and quart jars.
- Jellies usually give directions for half-pint jars.
- If you have a jar that is between sizes, use the time and pressure for the next larger size. For example, if you have a 24-ounce (3 cup) jar, use the processing time for a quart jar, or if you are processing jelly in a 4-ounce jar, use the processing time for the half-pint jar (8 oz.).
- Half-gallon jars are too large to allow adequate heat transfer to the center of the jar and should only be used for canning highly acidic apple or grape juice.
- One-gallon jars are not recommended for food preservation.
Commercial Jars a.k.a. One Use Jars
According to the National Center for Home Food Preservation, "Most commercial pint- and quart-size mayonnaise or salad dressing jars may be used with new two-piece lids for canning acid foods. However, you should expect more seal failures and jar breakage. These jars have a narrower sealing surface and are tempered less than Mason jars, and may be weakened by repeated contact with metal spoons or knives used in dispensing mayonnaise or salad dressing. Seemingly insignificant scratches in glass may cause cracking and breakage while processing jars in a canner. Mayonnaise-type jars are not recommended for use with foods to be processed in a pressure canner because of excessive jar breakage. Other commercial jars with mouths that cannot be sealed with two-piece canning lids are not recommended for use in canning any food at home."
Relevant Information about Canning Lids
Keep in mind some basic facts about canning lids.
- The standard canning lid is a two-piece lid consisting of a flat metal disk and a screw band.
- The bands are reusable unless they are rusty, bent, or dented.
- Use a new metal disk each time.Using the metal disk more than one time risks seal failure. The sealing compound on the lid is only guaranteed to seal once. When the sealant is heated during processing, it softens and takes the shape of the rim of the jar, forming a vacuum seal as the jar cools.An indentation forms in the sealing compound. The thinness of this indentation increases the likelihood of inadequate compound to flow over the glass rim of the jar if you attempt to reuse it.
- When sealed lids are removed from jars the first time, the lid is often bent slightly, preventing a proper fit on the jar.Use new lids each time.
Several off-brand lids are on the market. Some of these may create a vacuum seal. However, anecdotal reports from home canners tell us that many of these have higher rates of seal failure. If you choose to use them, follow the manufacturer's directions for preparing and using the lids. It would be good to check the lids for quality (or lack of quality) signs. Is the sealing compound uniformly applied?Is the metal disk symmetrical and the metal evenly coated?
Consumers have reported buying what they thought was a major brand of lid online, only to discover they were counterfeit. Minor changes to the labeling of the box and the print on the lid itself alerted the brand name manufacturer of the problem. Unfortunately, consumers ended up with lids that did not seal.
Reusable Lids
Reusable three-piece lids consist of a plastic or glass disk with a rubber or silicone gasket to create the vacuum seal. Preparation of the lids and gaskets, as well as fastening of the lids on the jar, will vary by the lid type and the manufacturer.It is necessary to handle the disk to apply the gasket before it is applied to the jar—a process that increases the opportunity to introduce bacteria from your hands onto the lid. Directions instruct you to loosely apply the lid to allow for venting during processing.After processing, you are instructed to tighten the screw band until the jar seals and cools.The disk is solid, and you are not able to see if the jar is sealed until you remove the screw band from the cooled jar. Like regular two-piece lids, you must remove the screw bands for storage. That is especially important in order to see if the jar is sealed. Lift the disk gently from the gasket to see if it separates to determine that the lid is sealed.Be aware that reusable lids are more expensive than two-piece lids. However, the gasket seals can be reused as long as they are not damaged or stretched out of shape, and the plastic or glass disks can be reused indefinitely. They can be used for pressure canning as long as the temperature inside the canner does not exceed 250°F.
Avoid Commercial Use Lids
Avoid the use of one-piece lids designed for commercial use.Do not reuse twist-off lids that come on pickle jars, spaghetti sauce jars, or others. Bail lids with a rubber gasket are designed for decorative use or dry food storage. There are some lids developed only for storage after the jar is opened; do not confuse these with canning lids.
Use Correct Canning Procedures
If you have a limited supply of lids, use the correct canning procedures to make sure that jars seal properly. Refer to Let's Preserve: The Basics of Home Canning to ensure you are using procedures to increase the likelihood of jars sealing. Remember to allow proper headspace, remove air bubbles, clean the rim of the jar, turn the band finger-tip tight, and process high-acid foods in a water bath or atmospheric steam and low-acid foods in a pressure canner.
Alternatives to Canning
If you cannot obtain canning supplies, you may need to explore alternatives to canning. Most canned recipes will freeze well including vegetables, tomatoes, salsas, and pie fillings. Using specific directions for freezing fruit, especially fruit in a sugar syrup, yields satisfactory results and a fresh fruit taste. Dehydrating is another option. Dehydrated vegetables can be reconstituted for soups, stews, and casseroles. Dehydrated fruits make great snacks and can be used to make tasty desserts or served plain as stewed fruit. For a fun treat try Strawberry Fruit Roll-Ups!
References:
National Center for Home Food Preservation. (n.d.). Recommended Jars and Lids. University of Georgia.
LaBorde, L.; Zepp, M.; & Hirneisen, A. (2023, March 1). "Let's Preserve: The Basics of Home Canning". Penn State University.
LaBorde, L.; Zepp, M.; & Hirneisen, A. (2023, April 13). "Let's Preserve: Drying Fruits and Vegetables (Dehydration)". Penn State University.
LaBorde, L.; Zepp, M.; & Hirneisen, A. (2023, May 22). "Let's Preserve: Freezing Fruit". Penn State University.
LaBorde, L.; Zepp, M.; & Hirneisen, A. (2023, June 8). "Let's Preserve: Freezing Vegetables". Penn State University.
Zepp, M. (2024, February 13). "Strawberry and Other Berry Fruit Roll-ups". Penn State University.
