How to Identify Antique Bottle Seams

Look at the side of the bottle you wish to identify and locate the seam that runs along it. The newer the bottle, the closer this seam will extend to the top of the bottle.

Determine whether or not the seam on your bottle ends below or on the neck. If the seam on your bottle ends on the neck or just before the neck of the bottle, the bottle was likely manufactured before 1860. The bottle's lip was applied after the bottle was complete and thus the seam does not extend to it. A two-piece mold was used from 1810 to 1880. Also, a cup mold was used from the 1850s to 1920s, on which a lip was applied. However, most bottles made prior to 1860 were glass blown and did not have seams.

Check to see if the seam runs all the way up the neck of the bottle. If the seam on your bottle extends all or most of the way up the neck, but ends before the lip of the bottle, the bottle was most likely made between 1860 and 1880 using a three-piece post bottom mold. It should be easy to determine that the lip was applied separately as was the practice for bottles made before 1900.

Determine if the seam runs nearly all the way to the top of the bottle, but not over the lip of the bottle. If the seam on your bottle continues through the top of the bottle, but does not go through or over the lip, then it was likely produced between 1880 and 1890. On these bottles, the seam usually ends one-quarter inch from the top of the bottle. These bottles were made using a closed mold with the neck and lip mechanically formed while the bottle was formed by blowpipe.

Trace the length of the seam on the side of the bottle. If the seam on the bottle extends all the way up the bottle and over the lip, then the bottle is more modern and was made from around 1900 to the present day. These bottles are made completely by machines.