I posted yesterday about my wonderful gift of old canning jars. These jars are all quite usable for home canning and I intend to use them as such. I really want to tell you more about the Gem jars, a uniquely Canadian home canning jar but thought I should discuss a few thought on jars and closures first. Before the canning police feel the need to inform me that the old glass jars with zinc lids and rubber seals are not approved by the USDA, I will explain further. First off, the USDA does not approve any home canning product. Instead the USDA makes recommendations based on their testing and it should be noted for a product to be tested by the USDA it costs the manufacturer. So smaller companies like Tattler that make reusable canning lids have not been tested by the USDA simply because of the cost factor.
In my opinion these jars should be used for display purposes only. First, the jars themselves are old glass so there are flaws such as bubbles and in the case of the smaller back jar with metal cap on it, the seam is rough at the top causing unevenness around the rim. Both types of closures would make it difficult to tell if there is a seal or not because there is no way for the lid to pop off indicating a seal failure. Second, the age of these jars make them antiques. In good condition, complete with caps are worth a bit of money.
Pictured are older metal bands (left), older deep standard mouth band for glass inserts and newer bands for metal snap lids or reusable lids (centre back) and zinc band (right). The older metal bands are smooth with the same type of finish as the newer metal bands. These can safely be used for home canning with glass lids or glass inserts. There are deeper to accommodate the extra width of the glass lid or insert and the gasket. The older zinc bands develop a whitish film much like hard water buildup so they take on a dull greyish appearance as well as a roughness to the touch. Although the USDA says it is difficult to easily tell if a jar is sealed, which is true of the porcelain lined zinc lids or the bail and wire closures, this does not apply to the glass lids, glass inserts or newer plastic discs.
The USDA recommends the metal snap lids because the manufacturers paid to have them tested. They are relatively easy to use with minimal seal failures and at one time were fairly inexpensive. It is important to note that when the USDA wrote their guidelines, the emphasis was on food safety which still holds true but the concern over availability of the metal snap lids or the fact they were single use was a non-issue. The USDA also was not concerned over the leaching of BPA into food from the plastic lining on the metal snap lids which we now know is a health concern. None of the reusable lids (glass or plastic) have been tested by the USDA so no recommendation has been made. Thousands of home canners are using all three types of lids and the plastic discs are growing increasingly popular. The only difference between these closures and the metal snap lids is the closure becomes a three piece system comprised of lid, gasket and band rather than two (metal lid with sealant, band). If anything, the glass lids, glass inserts and plastic discs (eg. Tattler, 4ever recap) are safer than the metal snap lids because there is no danger of a false seal that can happen if the centre of the metal lid is pressed before the jar is fully cooled. This will make it appear that the jar is sealed when in fact during storage is will quickly become apparent that it is not sealed. However, the problem arises if the band is left on preventing the lid from popping off the unsealed jar. In contrast, if a jar does not seal using a glass lid, glass insert or plastic disc it is immediately apparent upon removal of the band. The lid will pop right off! bottom line is the USDA recommends the metal two piece snap lids, recommends against porcelain lined zinc lids and makes no recommendation with respect to the glass lids, glass inserts or plastic discs all using rubber gaskets.
Rubber has the distinct problem of drying out and becoming brittle with age as pictured. This renders the gasket useless for home canning. The glass inserts that fit the standard mouth (70 mm) jars are vintage as are the rubber gaskets. Any rubber gaskets available are old vintage stock so may already be brittle depending on how they were stored. To date, I have found no source for new gaskets to fit these glass inserts. What this means from a canning perspective is the standard mouth glass inserts will only be useful until the gaskets wear out at which time it is unlikely a replacement will be found although there were sellers on eBay selling the gasket material so you could cut your own.
Now that I've discussed what jar closures should not be used for canning and why I consider the glass lids, glass inserts and plastic discs every bit as safe for home canning as the metal snap lids, I'll make a couple of points about self-sufficiency and being eco-friendly. Glass lids, glass inserts and plastic discs allow the home canner to be less reliant on finding a supply of the single use metal snap lids. At one time these lids were available even in the variety stores but no more. In our small community there are five stores which sounds like a lot but they only carry limited amounts and other than the dollar store the price for a doze is almost $3. The dollar store currently sells them for $1.50 and I have cleaned out their stock on several occasions! That means someone is out of luck until new stock arrive. Outside of the busy canning season, any canning lid supply in town practically dries up. In some areas, canning lids are available by mail order only. Re-usable lids make a lot of sense both in terms of cost and waste reduction while allowing the home canner to take advantage of canning opportunities without worrying about rushing out to buy metal lids. Re-usable is the eco-friendly approach as well. Each time I use a reusable lid I save a lid from going to the curb. Sure, it is the recycle bin but it is still waste that costs to recycle. At my level of canning, I am saving over a thousand lids per year from ending up in the recycle bin! Actually, I also saving that many aluminum cans from ending up in the recycle bin as well but that is another story. Tomorrow I will tell you all about the Gem jars!