Federal glass dating
The shift to the fully automated bottle machine from mouth-blown and some semi-automatic methods in the early 20th century is the classic example (Toulouse 1967, 1969a). The same bottle could have been recycled and reused many times for many years before finally being discarded - entire or broken (Busch 1987).
This was almost universal with many beverage bottle types (e.g., soda, beer, milk) but was variably common with just about any type bottle - especially prior to 1920.
The value of these highly collectible antiques varies greatly depending on a number of different variables including: There are a great many pieces of milk glass that do not have makers' marks or have lost their original labels which were attached with glue, making it difficult to identify the age and manufacturer of the piece.
Several helpful clues to use when trying to identify, evaluate and value a piece of milk glass are its: There are many antique reproductions and replications of antique and vintage milk glass pieces. Some are made using original molds, and are perfectly beautiful replicas of the originals.
Pontiled base fragments could also be from later produced "specialty" bottles which are described below.5.
Some bottle shapes are indicative of a particular manufacturing era, though many bottle styles/shapes were used for so many years - like the cylinder whiskey "fifth" or square snuff bottle - that the shape itself is not indicative of age.
(The two products were from separate companies which were cross-town [Sacramento, CA.] rivals during the late 19th to early 20th century.
This technology lag makes some diagnostic characteristics better than others for dating. As a corollary to #1, consider the following quote: "Treat terminal dates with care.
Produced since the time of ancient Egyptians, the striking translucent or opaque glass in various depths of white and beautiful creamy colors is highly desired by collectors.
The first pieces of milky white glass date to approximately 1500 B. when Egyptians used it for ointment jars and drinking cups.
An example of this is the finding of a few pontil scarred utilitarian bottles among otherwise late 19th or early 20th century refuse.
It is unlikely that this bottle was made during the same era, but instead was reused for a lengthy period or otherwise retained until broken or discarded.