It's that time of year to get a bit of canning done before the busy canning months start. This is a great time of the year to clean out the bones from the freezer that have been saved to make stock to free up a bit of freezer space in preparation for the arrival of our beef on the hoof purchase. I like running a full load (16 - 500 ml jars) in the pressure canner. A couple of weekends ago I decided to take a bit of time to can beef and turkey stocks. I ended up using two large beef soup bones for the beef stock and 2 turkey carcasses for the turkey stock.
At this point, many home canners would blame the reusable lids and go back to using the metal snap lids. That certainly happened when the manufacturers changed the metal lid colour from gold to silver, resulting in many complaints that the silver lids had a higher seal failure. In reality they did not as the only difference was the colour. Seal failures again increased when the manufacturers changed the plastisol sealant on the metal jars. The old sealant required the lids to be scalded but the new sealant only needs to be warmed. Over heating the new sealant results in seal failure so the real reason for these seal failures was user error.
I can't say I was happy about the seal failures but had to deal with them which meant doing a bit of trouble shooting. I put the stock into the refrigerator then washed the lids and rings well and set about making the turkey stock. The plan was to re-process the beef stock along with processing the turkey stock. Re-processing is as much work as the original processing. While stock can handle re-processing, some home canned foods cannot. If this type of food does not seal, the only choice is to refrigerate and use within a couple of days.
The following morning I removed the bands. Pictured are all of the jars beef and turkey stock (sealed and unsealed). The jar with the Tattler lid and one with a 4ever Recap lid that did not seal from the first processing sealed with the second processing. The two unsealed jars of beef stock from the first load to the right had 4ever Recap lids. They failed to seal with the second processing. All of the turkey stock sealed. By now I was getting a bit frustrated, having run the canner three times and still getting seal failures! In my mind though, there had to be another problem besides just the 4ever lids because of the three that had not sealed in the first load, one had sealed in the second load. The third load had no re-usable lids and no seal failures.
jars of beef stock fresh from the pressure canner, it is easy to see how boiling stock could actually be forced between the lid and rim of the jar. In this case, proper headspace had been left so I did not feel that leaking stock was the problem. There was no indication of any leakage in the pressure canner, reinforcing this conclusion.
Even though I used a funnel to fill the jars, I decided to use isopropyl alcohol (rubbing alcohol) to wipe the rims of the jar to ensure there was no oil on them. I normally do not do this as my jars go through the dishwasher just before using them so there should be no oil unless spilled on during filling which is unlikely but still possible when using a funnel. Many home canners routinely wipe the rims of their jars with vodka or white vinegar but I use a paper towel dampened with water.
Both Tattler and 4ever Recap reusable lids require tightening the band then turning back a quarter an inch for processing. As I tightened the band, it popped off. I tried again with the same results. I quickly poured the hot stock into another prepared jar, positioned the lid and tightened the band then turned it back. Once the jars were safely in the processing, I turned my attention to the jar. After trying four different bands, I realized the problem was not with the bands at all but rather the threads on this jar were defective. They were just off slightly yet the first time through the canner, a band had held just enough but did not tighten enough for the 4ever Recap lid to form a seal.
There is a misconception that new mason jars are flawless. This simply is not the case. I have seen brand new canning jars with air bubbles in the glass, small chips in the rim, a droop in the rim and slightly misshaped openings. It happens. A defective thread is a difficult one to catch and in fact if a band catches just enough, you might not catch it especially if using a boiling water bath canner.
Finally, after running the canner four times all my jars of stock were sealed. Two of those loads experienced seal failures. In total, there were 4 seal failures, 1 was Tattler, the other 3 were 4ever Recap lids. At the end of the fourth run, all lids had sealed. The only problem I found that accounted for one seal failure was the defective threads on one jar. I still have no idea why the other 3 lids failed to seal originally. There was nothing apparent that would contribute to the seal failure. I do not feel that any of the seal failures were due to the lids considering two brands of reusable lides were affected. It is possible that I did not turn the band back enough when putting the reusable lids on or I may not have tightened the band enough when just out of the canner even though I took great care during both steps.