I bought some big bags of both the "regular" and wide-mouth lids/gaskets several years ago and have never worried about the metal lids that come with the jars when they're new (got them saved in a separate box "just in case" and also use them occasionally when I'm gifting canned goods). There is a slight difference in the way to tighten the lids during processing, but the occasional "didn't seal" is usually my fault, and we just eat the contents of that jar sooner rather than putting it on the shelf.
If you do any volume, or don't want to get stuck without metal lids, I cannot recommend the Tattler lids enough! Be sure to get the originals; there are some knock-off brands which are not made with the BPA-free plastic, don't last as long, etc.
I guess the cans have the "clicky click" to ensure safety. But this is actually life-or-death: you don't want to mess this up at any step of the process.
We’re just making a gasket here, no?
I thought I'd try for a light syrup so I used 1/3 of the sugar - some recipes in the 1939 Kerr canning cookbook that I have called for that, with paraffin on top. Plus, I decided to reuse some of the previously used lids, being too cheap that specific year. They turned out beautiful to look at and went into my pantry
Well, about a month later, I was awoken in the middle of the night by explosion from downstairs. 2 jars exploded, most of those jars were fermenting, some had really nasty organic growth scum on it, and the cleanup was quite terrible. I think it was the lack of sugar, not the lids, but lid reuse didn't help.
Key takeaway - always use the right amount of sugar (1:1, even if it seems like you're pouring white death on), and never reuse lids.
Also..this is why I always preserve fruit in alcohol. Why not?
Botulism actually dies when in contact with oxygen. So you can only die to Botulism if you properly seal a can. Actually... you don't die to Botulism, but to Botulism's toxins. As soon as you open a can, Botulism dies. The leftover toxins however will kill you.
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You seal a can to protect it from all other infectious diseases: E. Coli, Black Mold, etc. etc. This stuff can kill you as well.
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"Normal" diseases die at boiling temperatures. So when you boil a can, its sufficient to kill off E. Coli, Black Mold, etc. etc. However, Botulism dies at higher temperatures... you need a pressure canner to raise the boiling point above 212F (!!!) to kill Botulism spores.
So the high-temperature is to kill Botulism. The sealing is to then keep all other diseases out after you've decontaminated the food.
Also works well for other "liquidy" things people usually put into jars.
When you can using those lids: you melt the sealant due to the high temperature (boiling, or above-boiling using a pressure-canner). The sealant forms an airtight-seal for the can, protecting your jams for literally years even at room temperature.
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For "normies" who don't can, use the grey plastic "Ball Leakproof Lid", which has numerous superior properties for non-canners. In particular: plastic does NOT rust, they're more eminently reusable.
With that being said: cheap one-time-use bands + lids are good for dry goods and non-sealing purposes. If you simply put your cans in the refrigerator, they're sufficient to be reused (as long as they don't rust).