Before this thread fades too far from currency, we need to set this story aright. I had hoped that someone would point out the irony within my post above. There WAS a gaffer involved with ground-lip canning jars, at least those made before the 1890s.
Here is a distillation of the murky presentation of facts from the Historic Bottles website:
As noted, the ground finish was more a method of finishing than a type of finish, since the functional parts of the finish were fully mold formed and not tooled to shape. Once the bottle or jar is removed from the blowpipe and usually annealed, the rough top surface of the finish (i.e. the rim) was ground down flat to facilitate closure sealing or simply to "finish" the jar.
Along with fire polishing, the grinding down of the cracked-off (or burst-off blow over) top surface of the lip or rim was one of the simplest methods for "finishing" a bottle since the functional parts of this finish were fully mold formed and not tooled to shape. Once removed from the blowpipe and annealed, the rough rim was ground down flat to "finish" the bottle and sometimes to facilitate closure sealing. The ground finish pictured to the left is on a Lightning fruit jar which dates from between 1882 and the early 1900s
Parison - An inflated gather of glass which is not yet the finished bottle. The term is applicable to both mouth blown and machine-made bottles. With mouth-blown bottles, a parison is the early expansion of the gather (gob) of glass which is then placed in the mold for final expansion to the mold induced form.
With machine-made bottles the gob of glass is sucked (Owens Automatic Bottle Machine), placed, or dropped (other semi and fully automated machines) into the parison mold which forms the parison. In the machine process, a parison is a preliminary bottle shape with a fully formed finish and a partially formed body. The parison is then automatically transferred from the parison mold to a separate blow mold for final blowing/shaping of the bottle body.
Parison mold - Also known as the blank mold, a block mold (on a press-and-blow machine), or on an Owens Automatic Bottle Machine it is sometimes called a measuring mold). This is the preliminary bottle forming mold on all automatic bottle machines which transforms a gob of glass into a preliminary bottle shape with a fully formed finish (lip) and a partially formed body.
The parison mold on a blow-and-blow machine was made of two or more parts (not including the neck-ring mold) This formative bottle is then automatically transferred to a blow mold for final expansion to shape of the finished product. . . . Parison molds were unnecessary with mouth-blown bottles were only one mold was used. See the Glassmaking & Glassmakers page for more information.
The blank (parison) mold concept was the revolutionary invention (patented in 1882) of Philip Arbogast of Philadelphia, PA. although the implementation of the blank [parison] mold - which forms the "finish" of the bottle - was not realized until the 1890s with the first semi-automatic machines (Howard 1950). [emphasis added]
