Around the turn of the century, the typical color of bottles changed from aqua to clear.
allowed the machine to make even small thin glass medicine bottles. One of these machines could make over 30,000 bottles per day. By 1917, an automatic machine could spit out over 60,000 bottles per day, which made bottles much more affordable to the masses. All bottles made by machine are referred to as automatic-bottle-machine or ABM bottles. Around the turn of the century, the typical color of glass used for bottles changed from aqua to clear. Fewer bottles were being embossed with unique individual manufacturers’ logos and by the late 1930s, painted label bottles became more cost effective to produce. Bottles lost their individuality as technology improved. Knowing the basic techniques of glassblowing, including how to identify free blown, mold blown, and automatic machine made bottles, and the unique manufacturing marks each leaves on the finished product, is the key to estimating a bottle’s age.
About The Author Capt. Dan Berg owns and operates the charter boat Wreck Valley and is a member of the Eastern Dive Boat Association. He has authored over a dozen books and was host and producer of the “Dive Wreck Valley” TV series. For more info on the author, visit www.aquaexplorers.com. March-April 2012 American Digger Magazine
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