Bottle Marks and Bottle Dating: A Field Guide

Step 1: Mouth-blown or machine-made?

Start at the neck. On a machine-made bottle the vertical side seams run all the way up the lip and over the top of the rim, and a horizontal seam usually circles the neck just under the lip.^[1][2][3] On a mouth-blown bottle the side seams fade out on the neck or just below the lip, because the lip was formed or finished by hand.^[1][2][4]

The split is the single most useful date line in American bottle glass. Most U.S. molded mouth-blown bottles were made between about 1820 and 1915, and by 1917 hand-blown containers were only about 5 to 10 percent of U.S. production.^[1][2][4] Semi-automatic press-and-blow machines were making wide-mouth jars and food bottles from the mid-1890s (sources differ between 1893 and 1894).^[2][3][4] Narrow-neck bottles followed with the Owens Automatic Bottle Machine.^[1][2][3][5]

A note on that machine’s date. Michael Owens filed the patent on April 13, 1903, and it issued as U.S. Patent 766,768 on August 2, 1904. Some bottles were made on it from October 1904; serious commercial production began in 1905.^[3][4][5][6] The familiar “patented 1903” is the filing year.

Two exceptions. Ground-rim fruit jars and flasks have seams that reach the rim but are mouth-blown: the rough top was ground off after blowing.^[1][2][7][8] And some early machine-made milk and ink bottles have seams that stop short of the rim.^[1][2]

Seam height on a mouth-blown bottle is not a date. A 1963 collector’s chart read the side seam like a thermometer: the higher it ran, the newer the bottle. Bottle Research Group authors tested it against securely dated bottles and found that seam height depended on the tools and the workman, not the decade.^[1][9] Only a seam that goes over the rim is diagnostic.

Step 2: Machine marks on the base

Turn a machine-made bottle over. A suction scar, a thin, feathered circle that is often off-center and can run up onto the heel, comes from an Owens-type machine, which sucked glass up into the mold. It can’t predate 1904 (in practice 1905) and is usually after 1910. Owens machines were replaced by gob-fed machines from the 1920s and went out of production around the late 1940s or early 1950s.^[2][3]

A small, neat valve mark centered on the base comes from a press-and-blow machine. It turns up mostly on wide-mouth jars, food and milk bottles, most often from the early 1900s through the 1940s. On a narrow-neck soda or beer bottle it points to the early 1910s.^[2][3]

Stippling, a field of tiny raised dots on the base or heel, was introduced by Owens-Illinois in 1940 along with its Duraglas glass and was soon copied across the industry. A stippled bottle dates from 1940 or later. A plain base doesn’t prove an earlier date.^[3][10]

A cup-bottom mold leaves no seam on the base and a seam just above the heel. It was used from about 1850 to the present and is the usual machine mold, so it dates loosely on its own.^[2][11] A round or oval seam inside the base marks a post-bottom mold. Bill Lindsey dates mouth-blown post-bottom bottles from the mid-to-late 1850s to about 1890; we found no second source for that range, so it isn’t in the tool.^[2][11]

Step 3: Pontil scars and smooth bases

A pontil scar is the rough spot left where a rod held the bottle while the lip was finished. On American utilitarian bottles (medicine, food, soda, liquor, ink) it usually means manufacture before or during the Civil War and virtually always before the early 1870s.^[2][8][11] By 1870 no more than about 5 percent of utilitarian bottles were pontiled, according to an estimate quoted on the SHA site.^[2][8][11]

The types overlap. A bare iron (“improved”) pontil leaves a reddish or black residue and mostly dates from about 1845 to the mid-1860s.^[8][12] Sand pontils and blowpipe or glass-tipped pontils fall under the same general ceiling; the SHA site gives narrower dates for each, but we found only that one source for them.^[12]

A smooth base on a mouth-blown bottle means it was held in a snap case, a tool that gripped the body and left no scar. Snap cases were coming in from the late 1840s, so a smooth-based mouth-blown utilitarian bottle usually dates after about 1855 to 1865.^[2][8][11]

Perfume, barber and other “specialty” bottles, demijohns and many imports kept pontils much longer. Use pontil dates for everyday containers only.^[2][8][11]

Step 4: The lip (finish)

Glass people call the lip the finish. On mouth-blown bottles its construction narrows the date fast.

Cracked-off or sheared

The bottle was simply broken or cut from the blowpipe and left rough or fire-polished. American bottles with this lip rarely date after the 1860s. (Newman’s 1970 dating key ends it about 1840; the SHA site puts the practical end at about 1870.)^[7][8]

Applied

A separate gob of glass was added to the neck and shaped. Look inside the mouth for a ridge or seam where the added glass meets the neck. True applied finishes typically date about 1820 to 1890; small druggist bottles switched to tooled lips by the late 1870s, big beer bottles by about 1895.^[7][8][11]

Tooled

The lip was formed from the neck’s own glass with a finishing tool, which also wiped out the side seams for up to an inch below it. Most tooled-lip bottles date from about 1885 to 1890 into the 1910s, and hand tooling largely disappeared between 1910 and the early 1920s.^[2][7][9]

Seam into the tooled lip

On late mouth-blown bottles the side seam runs up into the lip but not over the rim. These virtually always postdate 1895 and mostly date from 1900 to the early 1920s.^[7][9]

Ground rim

A flat, frosted top, mostly on fruit jars blown in a blow-over mold. It is common on mouth-blown jars from Mason’s 1858 patent on; wide-mouth ground rims faded out in the early 1900s and narrow-mouth ones about the 1920s.^[1][2][7][8]

Concentric tooling marks on the lip show hand finishing but date loosely: lipping tools were in use from the late 1820s until mouth-blown production ended in the mid-1920s.^[2][13]

Step 5: Molds, seams and embossing panels

If you find no side seams at all, the bottle was free-blown, dip-molded or turned in a paste mold.

• Free-blown bottles are often lopsided with soft, flowing lines. U.S. utilitarian bottles were rarely made this way after the 1860s.^[8][14]
• Dip-molded bottles have a molded body and a hand-formed shoulder and neck. The method had largely disappeared by about 1865 to 1870.^[2][14]
• Turn-mold (paste-mold) bottles were spun in a wet mold, which erased the seams and left fine horizontal rings and a glossy surface. Most date from about 1880 to 1915.^[2][14]

Among seamed mouth-blown bottles, a three-piece mold leaves a seam around the shoulder plus seams up the neck. Henry Ricketts patented his version in England in 1821, and such molds were used into the 1910s and 1920s.^[2][8][14] A hinge mold seam that runs straight across the base (with no pontil scar) mostly dates from about 1855 to the early 1870s.^[2][8][11]

Air-venting marks, tiny raised dots on the shoulder, body or in the lettering, were rare before 1880, common by the mid-1880s and standard by about 1890. Machine molds have them too.^[2][14]

Plate molds let a glassworks drop a customer’s lettered plate into a stock mold, which is why so much embossing sits inside a sunken or framed panel. The SHA site documents plate-molded sodas from the late 1840s; the Parks Canada glossary starts body plates with an 1867 U.S. patent and Whitall Tatum’s 1868 catalog.^[2][14]

Step 6: Glass color

Color helps, but only as a supporting clue.

• Sun-colored amethyst. Manganese was added to make glass colorless; ultraviolet light then turns it pink to purple. Popular use began by the mid-1870s and the practical end for most bottles is about 1920.^{[2][8][15][16]} The usual story, that World War I cut off German manganese, is incomplete: Lockhart and the SHA site both say the bigger reason was the tank furnaces of the new bottle machines, where manganese worked poorly.^{[2][8][15][16]} Bottles irradiated on purpose can be a deep purple, so color alone doesn’t prove age.
• Straw tint. Colorless glass decolorized with selenium (often with arsenic) shows a faint straw or amber cast in its thick parts. It’s typical of machine-made bottles from about 1912 to 1915 into the 1950s.^[15][16]
• Colorless bottles were uncommon before the 1870s and became the dominant bottle color once automatic machines spread in the mid-to-late 1910s.^[8][15][16]
• Black glass, so dark an olive or amber that it looks black, was mass-produced for liquor and ale bottles from the 1840s to the 1880s; American-made examples were uncommon after about 1880.^[8][16]
• Aqua and amber date poorly. The SHA site notes that aqua became uncommon after the 1920s except on sodas and some fruit jars, and that “old” off-shade ambers are rare after 1890; we found no second source for either, so neither is in the tool.^[15][16]

Step 7: Closures and patent dates

Crown-cap lips follow William Painter’s crown cork, patented February 2, 1892. Virtually all crown-finish bottles date after about 1894 to 1895; mouth-blown crown bottles run to about 1914 to 1915, and later ones are machine-made.^{[2][4][8][13][17]}

The Hutchinson stopper, an internal rubber gasket on a wire loop, was patented by Charles Hutchinson on April 8, 1879. It was probably the most common U.S. soda closure from the mid-1880s to about 1905 and effectively ended in the mid-1910s.^[2][13][18]

Lightning-type wire-bail stoppers were patented in the 1870s, and Henry Putnam’s jar version on April 25, 1882. They are still made, so they only set a floor.^{[2][8][13][19]}

Patent dates are floors. “MASON’S PATENT NOV 30TH 1858” appears on fruit jars made for decades after John Mason’s patents expired, including machine-made jars. Any embossed patent date only says “no earlier than,” and it may refer to the closure rather than the bottle.^{[2][8][13][20]}

External screw threads for metal caps were standardized across the industry between 1919 and 1924, according to the SHA site; we found no second source for that range.^[13]

Step 8: Words, labels and date codes

Applied color labels (ACL), baked-on enamel lettering, began commercially in 1933: Brockway offered them that February, and Owens-Illinois had experimented from 1931. Parks Canada gives 1934. They’re still used, so ACL is only a floor.^[2][3][25]

Duraglas in script on an Owens-Illinois bottle dates from 1940 (the trademark’s claimed first use is September 4, 1940) to about 1964, occasionally to about 1970 on old molds.^{[3][10][26][27]} The SHA site says block-capital DURAGLAS was embossed after 1963; Lockhart and Hoenig say the block-letter name belonged to a coating and was never embossed.^{[3][10][26][27]}

NO DEPOSIT NO RETURN / NOT TO BE REFILLED on a beer bottle dates from 1939, when the single-trip bottle was announced, and became industry-standard wording in 1941. Earlier one-trip beer bottles without the words go back to 1935.^[28][29]

Reading an Owens-Illinois date code

On an Owens-Illinois base, the number to the right of the mark is usually the year and the number to the left is the plant. Early codes are a single digit that repeats each decade, so a 0 can mean 1930 or 1940. Pick the decade with other clues: script Duraglas or stippling means 1940 or later, and two-digit codes spread from about 1943 to 1946. Code practice varied by bottle type and plant, and liquor bottles followed federal permit rules, so treat any single reading with care.^[3][10]