I am not an expert on the subject but I have read that it is because they were hand blown. That is where the tool that the glass blower used to blow air into the glass was attached.
Those bumps signify the mold that that particular bottle was made from. I verified it with Kerr Glass company when they wrote, "Dear Mary, Thank you for your interest in Kerr containers. Those bumps signify the mold that that particular bottle was made from." Sincerely . . . .
The most popular material for home canning jars is glass.
they are 25 dollars each
It is not safe to reuse commercial canning jars for home canning. The glass in home canning jars is thicker than in commercial jars and they are created specifically to work with 2-piece lids. It is also not advisable to use very old canning jars.
A canning kit generally includes wide-mouth canning jars, a funnel to fill the jars, and various utensils to handle the food you are canning. Some canning kits also come with a digital timer to measure processing time.
If you use fresh lids and the jars have been throughly cleaned and sanitized, you might be able to use them for canning.
You would want to have anything you're canning pretty hot when you put it in the jars, yes. Cold filling, sealing, and heating will cause jars to explode.
Yes, Mason canning jars are available at dry goods stores, grocery stores, and big box stores.
If you are asking about Ball-brand home canning products, that business was spun off in 1993. For information on Ball jars, the Ball Blue Book and other canning products, visit the Jarden Corporation at www.homecanning.com.
The general canning steps include reviewing procedure and equipment, washing canning jars using hot sudsy water,filling canner with water,and placing hot jars on cloth towels to avoid slippage while filling.
Bertha F. Olsen has written: 'Canning in glass jars in community canning centers / by Bertha F. Olsen and Esther H. Scott' -- subject(s): Glass fruit jars, Canning and preserving
There are many sizes of canning jars in metric and imperial measures. Standard imperial jars come in half pint, pint, and quart, and gallon sizes, and can be small mouth or wide mouth. Standard metric jars range from .20 to 5 liter sizes.