How to make seal on lever flip-top "Kilner" jars without spoiling sterilization?

Question

I have a lever flip-top "Kilner jar" like this one:

The seals look like this:

Everybody, including Kilner the company (who made my jar), says to sterilize the removeable rubber seals for flip-top kilner jars separate from the jars, by boiling the seals. However, I can't find anybody who says how one then re-attaches the seals to make the seal without spoling the sterilization. What does one do?

I feel that no part of the sterilizing process requires a video except for this one step, but every video I've found skips only this step. I suspect everybody is as unsure as me and that's why they fudge it!

If I try stretching it back on the jar with my grubby hands - I guess my hands are far from sterile even after I've washed them - I find it very hard to avoid touching the part of the seal that will be on the inside of the jar.

If I try resting the seal on the lower half of the jar before closing the lid, the seal flops half into the jar instead of sealing properly, no matter how I position the seal.

I guess I'll just wear rubber gloves and give them a good wash? How do you regular jar-sealers do this? Has an authoritative jar-sealing institution been brave enough to say how it's supposed to be done?

Answer 1

You may be a bit overcautious, there's a fair bit of leeway in preserving food due to the final processing steps.

Typically we clean and sterilize the jars by immersing them in a large pot with boiling water.

After some time (maybe 10 min) we remove and assemble the clean sterilized lids and rings. Large canning tongs are essential unless you have leather for fingers.

Keep in mind that everything is still hot, so assuming that you keep your hands clean, your handling shouldn't introduce any viable bacteria.

Now add the food, then close the lid and place the jars back into hot water and boil for 30 minutes, this will kill any residual bacteria. this might be the part you missed

The hot water heats the air inside the jar and causes it to expand and escape from the jar

Remove and let the containers cool off, this will cause the air in the jar to form a vacuum, sealing the contents.

References: My grandmother, my mom, me, these guys

Answer 2

You could try wearing latex/nitrile/PVC disposable gloves (powder free) and rub them all over with some 50-70% ethanol (hand sanitizer; don't use the gel ones, they leave residues). The ethanol is very effective against bacteria, but is not effective against fungi or bacterial spores.

You should also note that many (but not all) canning/bottling methods use a heating step after the food is put into the cans and you are adding very hot food to the jars, this heat should be pretty good at killing off any contaminants you leave behind. In addition, many canning recipes use things like acidity (low pH) or low water activity to help prevent bacterial and fungal growth.