Putting Food By - Janet Greene [34]
First, are there any directions, either printed on the container or on a separate sheet/folder inside the package? (A responsible manufacturer—one who knows home-canning, and has food safety in mind—will want us to use his closure in the way that gets good, wholesome results that store well.)
Next, if there are directions, do they make sense? Although they may be terse, do they cite with helpful clarity the steps required for using that particular closure successfully?
Then, do the directions say how to handle the particular closure after the processed jar of food comes from the canner? Do they tell us explicitly how this closure looks when the cooled jar has a good seal? Or whether, if it’s a conventional two-piece screwband type, the band may/may not be removed before storing?
And finally, do the directions say clearly that the steps they give cover only the procedure for using that closure? Do they therefore tell the home-canner to use an established guide for complete instructions on packing and processing specific foods? (Makers of canning-jar closures have an obligation to the people who use their products, and it takes only a few lines of print to give a land or e-mail address we can write to for a government bulletin—or for their own home-canning booklet, if they’ve been in the business long enough to have one. See the Appendix.)
Acceptable Characteristics for Its Type?
Is it well made and of durable material, able to withstand high heat for a maximum processing period without distorting? (A sleazy lid is unlikely either to behave well in a Pressure Canner at 240 F/116 C or to retain a seal after months on the jar.)
Does it have a ring of sealing compound that’s evenly applied? And sufficiently wide to cover amply the jar’s sealing rim?
Does the top have a degree of flexibility—meaning springiness—in the center? (On a well-sealed modern mason, all lids of this type will be slightly depressed in the center, which is pulled down by the strong vacuum created as the food cools after correct processing.)
Does it have a tiny down-turning flange that lets it seat securely, and properly centered, on the jar’s rim before the lid is held down by the band? (A piping-hot lid that slides back and forth on the jar requires some extra manipulation when we put on a piping-hot screwband. And the lid section of every two-piece closure must be set separately on the jar rim before the band is applied; even the most terse manufacturers’ directions make a point of doing this. Never clap the lid inside the band and then screw the whole business on as if it were the top to a peanut-butter jar, because the ring of sealing compound on the separate lid may not be wide enough to compensate for such treatment—which could force the lid so badly off-center that it fails to hold a good seal.)
The Types of Cans for Home-Canning
The containers called “tin cans” are made of steel and merely coated with tin inside and outside. This tin coating is satisfactory for use with most foods. These are called plain cans.
But certain deeply colored acid foods will fade when they come in long contact with plain tin coating, so for them there is a can with an inner coating of special acid-resistant enamel that prevents such bleaching of the food. This is called an R-enamel can.
Then we have still other foods that discolor the inside tin coating—perhaps because some of them are high in sulfur, and act on the tin the way eggs tarnish silver; or because some are so low in acid as to nudge or straddle the Neutral line. Although there’s no record of any damage to these foods from tin coating, there’s a can for them that is lined with C-enamel.
A leading manufacturer of cans for home-canning says that we may use plain cans and C-enamel cans interchangeably—except for meats, which always take plain cans—with the sole detriment that sometimes the insides of plain cans will be discolored.
Note that although there are many sizes of canned foods on supermarket shelves, the cans commonly used in putting food by at home are: No. 303—which holds about 16 ounces;