DATING MY OLD BOTTLE
Bottles Without Mold Seams
Check bottle for mold seams. The earliest bottles were made by a glassblower using a blowpipe, and free-blown bottles will lack seams.
Check for a pontil mark. A free-blown bottle will often exhibit a scar on its base from when the bottle was detached from the blowpipe (pontil).
Check for bottle symmetry. If the bottle lacks mold seams but exhibits a high degree of symmetry, it may be dip- or turn-molded and probably dates before 1850.
Bottles With Mold Seams
Check to see if seams go all the way from the base to the lip. If the seam disappears in the neck, then the bottle was probably "blown-in-mold," and dates circa 1800s to 1915.
Note if bottle has seams that extend all the way to the lip. These are machine made and date from the early 20th century and later.
Check for a "suction" scar on the base. Bottles with mold seams and suction scars are made in an Owens Automatic Bottle Machine and date after 1903. The Owens machine revolutionized the bottle industry, and made bottles very common objects.
Bottles with Labels and Embossed Lettering
Check for embossed lettering. Embossed lettering can date prior to 1850, but most date to the late 19th century and later. Embossed lettering is especially common on patent medicine bottles that date from the mid-19th century through the early 20th century.
Check for embossed lettering on the base. This often indicates the bottle manufacturer and will help date the bottle.
Check for the following lettering: Federal Law Forbids Sale or Reusw of This Bottle. These are liquor bottles that date from 1935-1960s.
Check for applied color labeling. These bottles date after 1940.
(Historic Glass Bottle Identification & Information Website)
Free-blown (no mold)
No mold seams
Asymmetrical and non-uniform
Up to about the 1860s in the archaeological record
Simple Two-piece mold (“Hinged mold”
Mold seam extends from just below finish, down the neck and side, across the bottom, and up the other side
Symmetrical, uniform shapes
May have embossed lettering on body, especially after 1869 Ca. 1810-1880 "Cup" mold
Mold seam on each side that extends from just below the finish down to the edge ("heel") of the base
Most-common technology in the late 19th and early 20th centuries (ca. 1850s-1920s) Post mold
Bottle made in a three-piece mold with separate base plate
Side seam continues onto base, then is interrupted by the circular (sometimes oval) post
Dominant mold type used between about 1870 and 1900
1840s–early 1900s (sometimes later) Ricketts mold
No mold seams on body; horizontal seam around circumference where body joins shoulder, and vertical seam part-way up each shoulder
Often used for liquor and pharmaceutical bottles 1820s–1920s Turn mold
Bottle turned while in mold, obliterating seams
Often used for wine/champagne and brandy bottles (usually dark green)
No embossed lettering; glass highly polished from turning in mold Ca.1870–World War I Automatic bottle machine
Bottles made by machine, rather than blown
Seams run all the way up the bottle and over the finish
Made in large numbers beginning after World War I (though the first machine was invented in the 1890s) Sheared lip
Bottle neck stretched and cut, end ground or re-fired to make smooth
Bubbles in glass also will be stretched and elongated; vertical stretch marks visible on neck
Pre-1860s Hand-applied finish
Bottle re-heated and ring of glass applied to neck by hand
Ring very asymmetrical, sometimes “globby” Ca. 1840-1860 Lipping tool Applied ring of glass smoothed into a more-uniform shape using a hand-held lipping tool
Striations around circumference of neck from lipping tool; mold seam stops at neck (obliterated by lipping tool)
After 1856 Automatic bottle machine
Entire bottle, including finish, made by machine
Lip completely symmetrical and even
Mold seam runs over lip
After World War I Interior-threaded
Screw-in top with plug inside bottle
Interior threads on bottle finish 1870s-1900
Exterior-threaded (“screw cap
Screw-on top with cap outside bottle
Exterior threads on bottle finish
Mid-1880s-present (threads standardized after 1924); metal caps on early examples, metal or plastic after 1930s Hutchinson “spring” stopper
Rubber gasket inside bottle neck, with metal-loop handle
Stopper could not be removed from (intact) bottle
1879-1915 "Lightning" stopper
Ceramic plug held in place by metal loop attached to metal ring around bottle neck
Bottle finish with wide, prominent lip to hold ring in place
1882-1920s (still used, but not in large numbers - think Grolsch Beer) "Crown" cap Metal, inverted-crown-shaped cap Bottle finish with narrow ring at top to hold cap 1892-present