Putting Food By - Janet Greene [32]
The jars come packed with their closures. The lids also are sold separately, with or without screwbands.
Availability of jars, and currently their North American makers, are listed in the Appendix.
HOW THE TWO-PIECE METAL CLOSURE WORKS
The lid—called “dome” or “self-sealing” or “snap” by the individual makers, but of one basic design—is a flat metal disc with its edge flanged to seat accurately on the rim of the jar’s mouth; the underside of the flange has a rubber-like sealing compound; the center surface next to the food is enameled, often white.
The lid is sterilized (more about this in a minute), placed on the clean-wiped rim of the jar of food, and then is held in place by the screwband, which is screwed down on the neck of the jar firmly tight—AND IS NEVER TIGHTENED FURTHER. “Firmly tight” means screwed down completely but without using full force, or without being yanked around as with a wrench.
The capped jar is processed, during which the “give” in the metal lid allows air in the contents to be forced out. As the jar cools, the pliant metal will be sucked down by the vacuum until the lid is slightly concave. You often hear the small plink as the lid snaps down, thus indicating that the jar is sealed.
STERILIZING JARS AND TWO-PIECE LIDS
Wash jars, screwbands, and lids in hot soapy water, rinse well in scalding water. Containers and closures that will be processed in a Boiling–Water Bath or Pressure Canner need not be sterilized further: but do let them stand filled/covered with the hot water until used, to protect them from dust and air-borne spoilers.
Containers for food that will not be processed or “finished” in a B–W Bath at 212 F/100 C at the sea-level zone must be sterilized. Wash jars and closures as above. Stand open jars upright in a big kettle, fill with hot water until the jars are submerged; bring the whole thing to boiling, and boil for 15 minutes. Remove the kettle from the heat but let the jars stay in the hot water.
Clean and scald the screwbands the way you do jars.
But scald, or boil, the metal lids according to the manufacturer’s directions.
This isn’t a cop-out: the makers give different instructions here, and all of us consumers must assume that they know what’s best for their own product. The result in every case is to sterilize, though; and all the lids are left in the hot water as a protection against dust, etc.
WHAT IS RE-USABLE
You should NEVER use the lid itself again for canning: the sealing compound on the lid will not seal right a second time around. And besides, it is ever so slightly warped now because you pried it off (and it may be punctured to boot). We scratch a big fat “X” on used lids on enameled or painted outside surface, then wash and toss them in a catch-all drawer to use sometime on a refrigerator-storage jar.
You of course can use the jars over and over again as long as they have perfectly smooth sealing rims, and have no cracks or scratches anywhere—including the minute scratches inside from digging out contents time and again.
You can use the screwbands again for canning, unless they’re rusted, or bent, or the threads are marred—all signs that they’re too tired to be safe in canning. (We often use “retired” screwbands for extra support under a springy wire rack in the bottom of our B–W Bath kettle, or to hold jars well apart in the canner.)
Old-style Bailed Jars with Glass Lids
Not recommended for Pressure Canners because they’re likely to be battle-weary, these haven’t been manufactured since the early 1960s—but there are still thousands around. Sometimes called “lightning” or “ideal” type, they have a domed glass lid cushioned on a separate rubber ring that seats on a glass ledge a scant ¼ inch down on the neck of the jar. The lid is held in place during processing by the longer hoop of the two-part wire clamp.
As you remove the jars from the canner after processing, snap down the shorter spring-section of the clamp so it rests on the shoulder of the jar. This is what we mean by “complete