Old canning jars are beautiful, but they are likely not safe to use in home canning.
PHOTO: FOTOLIA/ANNE KITZMAN
Like you, perhaps, I inherited several dusty cardboard cartons of old-time canning jars. Some were equipped with a wire bale that clamped down on a heavy glass lid. Others had a screw-on lid of soft zinc, with glass lenses rattling in the center. Forgotten names such as Crowne, Atlas and Mason were molded into the glass. Some were even made of bubbly green glass of varying thickness, handblown into 18th-century molds. All required a round red rubber gasket between lid and jar to make a seal.
For years, the gaskets were nearly impossible to buy, so l never tried using the jars to put up food. Instead I filled them with old nails and other shop and barn junk. They will remain so employed, even though old-time rubber gaskets have once again become readily available for use on a new generation of high-fashion jelly jars imported from Germany, I believe.
Don't be tempted to resurrect your old rubber-gasket canning jars or to put up anything but high-acid jelly in the new ones. The technology is at least 100 or so years obsolete. You need to insert a knife under the lid to break the pressure seal, and few old jars have unchipped rims. Even if in good shape when filled, the rims of old jars can chip or lids can warp under pressure and ruin a good seal. Weak old glass can break under pressure and spew canned tomatoes all over the jelly cupboard. Worst, the seal formed by a rubber gasket pressed between uneven old glass and aged lids can fail and admit air without your being aware of it.
Get new-style canning jars. Widemouthed jars are easier to fill with chunks of meat, peach halves and such. You can sell really old canning jars as antiques. Slightly used modern jars can be a bargain if clean and unchipped. Sometimes heirs will sell off grandmother's old canning jars, still full of decades-old produce. You'll have to dispose of the suspect food, scour jars inside and out and use steel wool or an edged tool to remove the corroded old lid gaskets from the rims (using a knife or putty knife is sure to chip the glass). Hardly a bargain—at any price.
For more information, see Home Canning and Storing Foods Safely, Vacuum Packing and Nitrogen Packing Foods, and Best Ways to Preserve Vegetables and Fruits.