Canning jars are glass containers that are specifically made for home canning and preserving. Also called Mason jars or Ball jars, canning jars come with a flat seal and twist-on lid. The jars and lids can be reused over and over for years, but the sealing disks must be replaced after each use.
When you buy canning jars for home use, keep these things in mind.
- Canning jars come in many sizes. The most common sizes are half-pint, pint, quart, and half-gallon, but most canning recipes use the pint and quart sizes.
- Half-pint canning jars are perfect for jams, jellies, spreads, relishes, and sauces. Their small size make them perfect to add to gift baskets or to put together an assortment for gift-giving.
- Most vegetable, pickle, and salsa canning recipes call for pint or quart sized canning jars. These fit easily into hot water bath canners as well as pressure canners.
- Half-gallon sized canning jars can be difficult to use. Their large size requires extra large canners, and once full they are rather heavy and awkward to store.
- The flat sealing disk that comes with new canning jars has a sticky compound around the edge. When heated, the band creates a seal over the jar which makes the jar airtight. When you use your canned food, the screw-on lid ensures that the disk stays in place after the seal has been broken.
- Screw-on lids can be reused as long as they are in good shape. If they get dented or begin to rust, they must be replaced. Sealing disks can only safely be used once; after the first use, the sealing compound is no longer reliable to keep your food safe from mold or bacteria. Lids and sealing disks can be purchased anywhere you find canning jars.
- Make sure all of your canning jars are free of cracks or chips. They also need to be sterilized before use. Follow the directions on the box or leaflet that accompanies your jars to sterilize them. If you purchase second-hand canning jars, wash them with very hot, soapy water and boil them in a hot water bath for about ten minutes.
- Canning jars come in regular or wide mouth styles. The wide mouth jars are best for larger vegetables, fruit halves, and whole pickles, or anything that needs a bit of extra room at the opening.
- Never use jars that aren't specifically designed for home canning. Product jars from the grocery store cannot be reused as canning jars as the glass is not made for this kind of treatment.
- Old canning jars can be valuable collectibles. If you want to start a collection of canning jars, look for those with a colored tint. These are very rare, and actually work better at keeping food fresh because they allow less light into the jars than clear glass.