Many people have old bottles and don't know how to tell how old they are. Since bottles can be very valuable and collectible, knowing the approximate age of a bottle can help you sell them for top dollar. Bottles have sold for a few dollars to more than nearly $100,000 dollars for just one bottle on the antiques market. It happens. I met someone who didn't know the age of their bottle and sold it on eBay for $1,200 to somebody who knew it was really worth $60,000. There's more to the story you've got to read. To identify the age of your bottle, let's start from the bottom up.
What to Look For
The Bottle Base
The base of a glass bottle will tell you a lot about its age. In the middle of the 1800s, a snap tool was invented which let a glass blower or gaffer hold a glass bottle without a rod. This tool eliminated the sharp pontil mark (the broken end of the glass rod) at the base of a bottle. So, the lack of a pontil mark is actually a clue to age. Old liquor, spirits, medicine and bitters bottles all had various types of bases.
Circa 1855-1875, key molds were used on bottles which looked like a semi-circle on a bottles base. Later, about 1900, cup mold bases were used and they were smooth with no marks; sometimes on old bottles and flasks, too.
Possibly the most common type of bottle base is the push-up base. Used in mouth blown bottles such as wine bottles, the push-up base has an easily recognizable center which is pushed-up into the bottle's base that allows wine sediment to collect in the ridge that continues around the perimeter of the bottle base.
The Bottle Top or Lip
The bottle top or lip of a bottle comes in many forms. There are cork tops, screw tops, crown tops, etc. Common since the 18th Century, corks led the market because corks could be impressed into the top of a bottle and seal it no matter the form of the bottle.
Screw tops were invented in the early 1800s, but not standardized so they would not come into their own until the era of machine-made bottles in the 1900s.
Crown tops were a Victorian innovation, circa 1890s. They also did not come into widespread use until the era of machine-made bottles in the 1900s. Look for these old bottles with the characteristic crown top.
The embossed maker's mark or letters on the side of a bottle or on the base of a bottle will help to reveal a bottle's age. Marks or letters on collectible milk bottles and Coca Cola bottles are commonly indicators of age and origin. The letter form for "S" was so hard to form on a bottle that it is often mis-shapen, deformed, reversed or eliminated. Missing letters, spacing that is not uniform with other letters, or other visible mistakes can help you date a bottle's age.
Get an online appraisal report of your old bottle from Dr. Lori.