I learned canning when I was a little girl with my Grandmother, & Mother and have taught my own girls how to can. We have been very successful with not havind unsealed jars. We have canned close to 100 25# boxes of tomatoes this year. Salsa, Stewed, Chili Sauce & Spag Sauce to name a few. We have followed the new rules to a T and still have several in a batch that do not seal with these new lids. We did 34 jars on Monday, waited the 24 hours before moving or washing them. Checked several times and found 5 that did not seal so I put new lids on and reprocessed them and they seemed to have sealed. When I went to wash the jars to store them, removing the rings found 2 more that had not sealed but I had previously checked the lids by touching and they were all sealed and indented. We want to make vegetable based soup to store for the winter but am afraid now to do it and put them on the shelf for fear the lids will pop and they will spoil. TRASH THESE NEW INVENTIONS AND GET BACK TO THE BASICS.

The Mason patent was for a threaded lid which could be used in conjunction with a threaded jar rim. It's generally a canning jar, but not necessarily. As you surmised, if the two-piece Ball or Kerr lids fit, there's no reason not to use it for boiling water bath, but pressure canning introduces stresses well beyond that. The only jars I would use for pressure canning are Ball and Kerr. Carol

I know we've discussed this before, and I often re-use mayonnaise jars and spaghetti sauce containers, pickle jars, etc. I don't use them for pressure canning, as I tend to get more breakage, but have experienced no more problems with my "recycled" jars than I do with commercially available Ball/Kerr jars. This is from the National Center For Home Food Preservation: "Most commercial pint- and quart-size mayonnaise or salad dressing jars may be used with new two-piece lids for canning acid foods. However, you should expect more seal failures and jar breakage. These jars have a narrower sealing surface and are tempered less than Mason jars, and may be weakened by repeated contact with metal spoons or knives used in dispensing mayonnaise or salad dressing. Seemingly insignificant scratches in glass may cause cracking and breakage while processing jars in a canner. Mayonnaise-type jars are not recommended for use with foods to be processed in a pressure canner because of excessive jar breakage. Other commercial jars with mouths that cannot be sealed with two-piece canning lids are not recommended for use in canning any food at home." Given the above statement, the premise that "Mayo type jars, as I know, have never been approved for preserving good products long or short term" is incorrect, they have been and still are "approved" for limited use. So, it's perfectly fine to re-use those mayonnaise jars and such, if you have them available. Even the Goverment and the widely recognized experts above say it's OK. Grandma did it, and I have some of the old wide mouthed marshmallow cream jars from back when they were still glass. Grandma used the stuff in fudge so she had several and when she quit canning she gave them to me. They've held at least 20 years worth of sweet relish and salsa, I like the size and shape for that as the product is easily accessed. Why do I use them when I can easily afford to just buy new commercially available jars? Because I don't like to buy things I don't need, I like to reuse/recycle/re-purpose all I can, and I don't like useful items to end up in landfills when it's not necessary. In spite of recycling centers, most things don't get recycled, and more resources must be used to produce more jars, so that they can then be thrown away. It's just not sustainable or ecologically sound. Matthias, it's good to know that those plastic lids fit the jars. I like to use them when storing a jar of something that wasn't completely used up, and the newer/thinner lids get bent by my can opener to the point where the ring doesn't screw all the way down and the jar isn't completely sealed shut. I also use my old "vintage" blue Ball jars for storing lentils, beans, rice, popcorn, and as refrigerator containers for leftovers. Sometimes in canning season I'm right down to my last lids, so I don't want to "waste" a good flat on a storage container. Annie

You would get more answers if you would post to the Cooking forum.