Dating antique milk bottles
Early milk bottles were made using the Owens Automatic Bottle Machine which left a round scar on the bottom of the bottle.The Owens machine used suction to pull molten glass into a mold and the glass was then cut by a knife which left a scar mark.The middle picture shows an open pontil on the base of a cylindrical medicine bottle.The third picture shows the base of a milk bottle from just after the trun of the century.The first milk bottle in the United States is normally credited to Harvey D.
In the late 19th century, milk was routinely scooped directly from the farmer’s churn into jugs that customers would leave on their doorsteps.
Some early mouth blown bottles were blown in a three piece mold.
The three pieces produced the base and the two sides of the milk bottle's body.
Only a few years ago bottles in these two categories rarely brought more than a few dollars but as interest in these categories increased so did the price. Whenever demand increases or outstrips the supply of a collectible, the price goes up.
Digger Odell's Antique Bottle & Glass Collector Magazine Price Guide Series has volumes different categories listing thousands of antique bottles that have sold at auction.