Prior to the advent of internal stoppers, soft drink bottles were typically sealed with corks. A bottler started by using a tin dipper and funnel to pour a small quantity of syrup into a bottle, and then took the bottle to the carbonator. While grasping the bottle with one hand, he held the bottle’s mouth tightly against a leather-packed spigot with his knee, and opened the carbonator spigot with his other hand, allowing carbonated water to flow into the bottle. Trapped air pressure in the bottle stopped the flow of water as the bottle filled, requiring the bottler to ease the seal against the spigot, releasing the air (a process known as “snifting”) two or three times before the bottle was filled. Since carbonic acid gas is heavier than air, the air would be forced out first. Becoming a proficient “knee bottler,” as they were called, required many years of experience.
With the bottle filled and carbon dioxide continually escaping, the bottler used a wooden or rubber mallet to quickly drive a cork into the mouth of the bottle. Carbon dioxide filled the space between the surface of the liquid and the bottom of the cork, exerting tremendous pressure on the cork, so corks were typically secured by twine or wire wrapped around the neck of the bottle below the blob top and over the top of the cork. Henry W. Putnam’s 1861 syrup gauge patent mentioned that another benefit of securing the corks with twine or wire was “overcoming entirely the common difficulty arising from flies.” Following the introduction of Putnam’s 1864 stopper fastening patent, the corks in most blob top soda bottles were held in place with a Putnam-type wire stopper. Once the corks were wired down, bottles were placed into wooden cases for delivery.
The blob top bottling process was not only slow, it was quite dangerous. Bottlers reportedly kept a very firm grip on bottles while adding carbonated water, as internal pressure often caused bottles to burst, particularly those with manufacturing flaws or damage such as cracks. The force of an explosion could often be contained by a gloved hand. If not contained, glass went in all directions. Although the soft drink industry was still in its infancy prior to the U.S. Civil War, the estimated 123 plants in operation in 1859 produced 67 million bottles of pop annually. It is amazing to realize the intensive hand labor required to fill that many bottles.