reusable canning lids

[thock]

I recently came across some reusable canning flats (see here). They are made of acetal copolymer, which is a type of plastic similar to Delrin, but which is less likely to absorb water. At room temperatures, it is inert, but I'm concerned that it would outgas formaldehyde at higher temperatures, particularly those found in your average pressure canner. (And yes, I see that they say formaldehyde forms at temperatures way in excess of 250 F.)

Which led me to a search for glass reusable flats. Interestingly, glass flats used to be made. I found some on eBay. They, like the Tattler lids, take rubber gaskets (but I'm not sure they take the same size), and it looks like they take slightly deeper rings to account for the extra thickness of the glass.

I wonder why they are no longer manufactured. Cost-prohibitive, perhaps? As the Weck jars that are readily available online use rubber gaskets as well, I'm wondering if it would be safe to use these older glass flats, assuming I can find appropriate gaskets. I know the NCHFP does not recommend the rubber gaskets, but I believe the Weck jars are used fairly commonly in Europe. I have not done any searching on European recommendations for canning.

Has anyone ever tried these glass lids? If so, what was your experience?

ETA: link to MSDS for acetal copolymer (formaldehyde outgassing)

Edited February 25, 2011 by thock (log)

[andiesenji]

I recently came across some reusable canning flats (see here). They are made of acetal copolymer, which is a type of plastic similar to Delrin, but which is less likely to absorb water. At room temperatures, it is inert, but I'm concerned that it would outgas formaldehyde at higher temperatures, particularly those found in your average pressure canner. (And yes, I see that they say formaldehyde forms at temperatures way in excess of 250 F.)

Which led me to a search for glass reusable flats. Interestingly, glass flats used to be made. I found some on eBay. They, like the Tattler lids, take rubber gaskets (but I'm not sure they take the same size), and it looks like they take slightly deeper rings to account for the extra thickness of the glass.

I wonder why they are no longer manufactured. Cost-prohibitive, perhaps? As the Weck jars that are readily available online use rubber gaskets as well, I'm wondering if it would be safe to use these older glass flats, assuming I can find appropriate gaskets. I know the NCHFP does not recommend the rubber gaskets, but I believe the Weck jars are used fairly commonly in Europe. I have not done any searching on European recommendations for canning.

Has anyone ever tried these glass lids? If so, what was your experience?

ETA: link to MSDS for acetal copolymer (formaldehyde outgassing)

These lids are made in the USA under rather strict guidelines. I would not hesitate to use them for canning.

I have quite a few of the "vintage" glass flats with the zinc bands but they are all for small mouth jars and for canning I use large mouth.

I can tell you that the glass "flats" are subject to chipping around the edges if one does not unseal them with care.

I have a number of the old "green" Ball jars but use them only for display and for dry storage.

Edited February 25, 2011 by andiesenji (log)

[thock]

Yes, I've seen that there are a greater abundance of the regular-mouth glass lids than the wide-mouth ones. I, too, like to can in wide-mouth jars, but unfortunately, most of my jars are regular-mouth, and since I got them very cheaply, I don't want to get rid of them, yet.

I figured that the glass ones might chip easily. They recommend using a butter knife between the ring and the jar to open them, which strikes me as asking for chipping. But the Tattler ones recommend the same opening method.

I am leery of using plastic in a high-heat situation. Glass has been around for a lot longer, and I just feel more comfortable with something that I KNOW doesn't outgas.

That said, the "normal" canning lids are coated with a plastic that contains BPA, so it's not like I'm canning without risks of exposure, although those risks are smaller than those assumed by using commercially-canned products.

It would please me no end to see someone manufacture newer glass lids, but I know that's a pie-in-the-sky dream.

Thank you for your comments, Andie. They are much appreciated.

[thock]

Andie,

Do you know if the rings used with the glass flats are meant to stay on the jars, or if they're supposed to be removable, like modern rings, once they're sealed?

[andiesenji]

Andie,

Do you know if the rings used with the glass flats are meant to stay on the jars, or if they're supposed to be removable, like modern rings, once they're sealed?

They remain between the jar and the lid until opened - they are what makes the jar seal.

Once opened they can be washed and reused for dry storage and etc., unless they get brittle and crack. As long as the rubber is supple, they are good, however I use new rings for canning.

This is a safety factor. With the metal flats and rings, there are specific instructions to NOT reuse the flats.

These zinc lids with an integral glass top liner to be used with wide rubber rings were still in common use when I was a child and my folks used them, always buying new rings for the jars because they knew from experience that it was safer to use new ones.

[thock]

They remain between the jar and the lid until opened - they are what makes the jar seal.

Once opened they can be washed and reused for dry storage and etc., unless they get brittle and crack. As long as the rubber is supple, they are good, however I use new rings for canning.

This is a safety factor. With the metal flats and rings, there are specific instructions to NOT reuse the flats.

These zinc lids with an integral glass top liner to be used with wide rubber rings were still in common use when I was a child and my folks used them, always buying new rings for the jars because they knew from experience that it was safer to use new ones.

I'm sorry, I think I was unclear in my question. The rings to which I was referring are the screw bands, not the rubber rings. Must the screw bands remain in place? At the top are the screw bands in question.

Thanks!

ETA link

Edited February 27, 2011 by thock (log)

[Icanmakeit]

I recently saw an ad in a magazine for the Tattler lids. I have never tried them but they look interesting.

http://www.reusablecanninglids.com/

I do a lot of canning and not having to keep buying lids over and over again would be great. I would probably keep using the standard lids for items being given as gifts.

A good idea I am going to try.