Canning Jars

Canning Jars

My Grandma Snider preserved produce of every kind and jars of brightly colored food stuffs filled her root cellar – mincemeat, crab apples, sweet and dill pickles, green and yellow beans, sauerkraut, pickled beets, rhubarb, gooseberries, jams, jellies, apple butter, applesauce… As a kid, I took it all for granted. But I recently researched the development of the canning process, glass jars, and even glass. I knew that obsidian is nature’s glass, created by rapidly cooling volcanic magma. How did we come to use a manmade material for food storage that is similar to the natural material Native Americans flaked and used for skinning knives?

Two independent writers of ancient times wrote that sailors moored by a river prepared a meal on the beach. Their ship carried nitum (perhaps trona or limestone) which they used to prop up their pots. When heated by the open fire, the nitum mixed with beach sand, resulting in streams of translucent liquid-glass. Glass making was a palace industry for the wealthy in the early centuries of development and there are numerous archaeological gaps in the existence of glass because it was a luxury material not made during harsher times. The first manual that has been found on glass making is from 650 BC in the tablets of the Assyrian King Ashurbanipal.

The Ashurbanipal library was in Nineveh, Mesoptamia (modern Iraq) and was not the first library of it’s kind, but is one of the few that survives to this day. The collection contained 20,000 to 30,000 tablets from about 1,200 complete texts in cuneiform, writing using wedge shaped characters. The library was housed in several rooms according to subject matter with a content listing at the entrance to each room, much like a modern library. Housed separately and securely were findings of spies and state secrets; other subjects included history, government, religion, magic, geography, science, and poetry. Included in these tablets are instructions in glass making.

The Egyptian civilization may be best known for preservation in jars. Ancient Egyptians brought mummification to a fine art and before they refined the process, the internal organs were removed from the body and placed in canopic jars. From ancient to more modern times the jars were carved of wood then stone, formed of pottery, and finally made of ceramic or porcelain. The jars initially had plain lids but more modern lids depicted heads, possibly to represent the dead. By the Eighteenth dynasty (1550-1292 BC) the lids often depicted the sons of Horus, which were the gods of the cardinal compass points. Each god protected a particular organ: the jackel-headed protected the stomach, the baboon-headed protected the lungs, the human-headed protected the liver, and the falcon-headed protected the intestines. There was no jar for the heart because as the seat of the soul it remained inside the body, but all of the organs were preserved because the Egyptians believed they would be needed in the afterlife.

After Alexander the Great’s death in 323 BC to the death of Anthony and Cleopatra in 3BC advancements in glass making included making core formed vessels and glass table wares. These were followed by slumping viscous but not molten glass over a mold and mullefiori, which means “thousand flowers”. Panes of multi colored glass were sliced, arranged, reheated and fused in a mold, resulting in a mosaic effect. Techniques for creating colorless or decolored glass were also developed.

In the United States there is evidence of glass manufacture on Jamestown Island, VA, with the earliest colonizers. Germans that arrived on the second supply ship, the Mary and Margaret, used James River sand, potash from the nearby forest and lime from burning oyster shell beds to make glass. Their products were the first exports from the New World, the first manufacturing done in America. Three furnaces were used to make glass: the smallest preheated the ingredients, the largest melted the glass, and another smaller furnace annealed or cooled the finished glass. Glass production was discontinued during the Starving Time of 1609. Also similar to ancient times, In America, from the earliest times through the 1800‘s, owning glass symbolized wealth.

Napoleon deserves credit for preserving food in glass – he offered a reward for a way to provide wholesome food to his soldiers and in response chef Nicholas Appert developed hermetic, or complete and airtight sealing. From providing food for the military, food preserving became common on small farms in the last half of the 1800s. It provided an alternative to salting, pickling, drying and smoking. In step with safe food preservation came the development of better containers. By the mid 1800’s crude glass and earthenware containers were sealed with corks, plugs, and parchments. Another poor alternative was food stored in tin cans with soldered tops, which often were not airtight and lead to spoilage. Glass jars held advantages over metal cans – glass could be reused, it was relatively inexpensive and light, stored easily and the acids in foods did not react with glass as it did with metal.

In 1861 Louis Pasteur discovered that a microorganism in unsterilized food caused spoilage. Thereafter, the food as well as the container were sterilized. Hand in hand with Pasteur’s discovery, 26 year old John L. Mason patented a sealing design for glass jars that included a thread molded into the top of the jar with a zinc lid and rubber ring that threaded onto and sealed the lid to the jar. Home canning in glass was popularized even more during World War II because steel and tin were needed for the war effort, and the Government encouraged people to grow and can their own food. Glass lids replaced tin and zinc, and smaller openings that used less metal in closures became popular. Home canning declined after the end of the war as there were fewer small farms, with a corresponding rise of supermarkets in the 1950s and 1960s.

Collecting canning jars has become popular as many have become antiques. They range in value from $2, $10, to hundreds and even thousands of dollars. To determine the time period in which a jar was made, the jar should be examined from top to bottom, following these guidelines.

  • Jars that predate 1855 were made by a glassblower so they have a pontil scar, which is a small indentation on the base, a ring of black and red iron. The pontil scar was formed when a glassblower held the item on a pontil rod when it was hot while the neck or lip was shaped and hand finished.
  • Jars with rough ground tops were made before 1900. The glassmaker ground off “blow over”  – the gob of glass resulting from attaching a blow pipe when the glass was blown into a mold.
  • Prior to 1915 the jars were free blown so had no mold seam, or they may have a seam that stops below the lip if the bottom was blown into a mold then finished by hand.
  • After 1915 jars have two mold seams from the bottom, up to and across the top as a result of being machine made.
  • If base has round ring in it and the lip is smooth, the jar was machine made after 1900 but before the 1930s.
  • Jars made between 1900 and 1930 in an Owens machine have a large rough jagged ring on the base.
  • Jars made by machine after 1930 have a more modern look with small scars on the bottom.
  • Jars that have turned purple were made before WWI. Chemicals are added to turn glass from it’s original aqua-blue or green to clear. Before World War I manganese oxide, primarily from Russia, was used in making glass. The manganese oxide reacts in sunlight and causes a color change to purple. During the war, Russian materials were not available because of German blockades so manufacturers started using selenium which does not react in sunlight. Manufacturers continued using selenium after the war.

I tend to clean and toss rather than surround myself with relics simply because they are old. Until recently, glass jars held no interest for me. But I doubt that I’ll see old jars in the same light – I’ll think of glass discovered by accident on a beach in Iraq over 3500 years ago, of the first manufacturing in the New World, of Napoleon’s search for safe food for his soldiers, of my Grandma’s root cellar, and I’ll appraise the jar for pontil scars, mold seams and color before I decide if it’s worthy of taking up my limited shelf space.