Hobbies And Interests
Things You'll Need
Instructions
Read books on the history of glassmaking to familiarize yourself with bottle-making techniques in different time periods.
According to the website Antique Glasshouse.com, you should check the bottle for seams. The alignment of a bottle's seam will help determine the time period it dates from. For example, a bottle with a seam that stops before the lip of the bottle was probably blown in a mold and may date to a period before 1910. Bottles manufactured after 1910 have a lower value on the collector's market.
Look for makers' identifying marks, which may include a manufacturer's seal, a date or a registration number. You can use these identifying marks to date the bottle. For example, by tracing the manufacturer's seal to a specific manufacturer, you can discover when that manufacturer was making bottles. Putting a registration number on a bottle was an English custom. The date of manufacture can be traced using this number.
Examine the shape of the bottle, bottle closures, bottle bases and other characteristics. The Antique Bottle Collector's Haven website says that all of these provide clues to the era in which the bottle was made. For example, smooth bottle bases are characteristic of bottles made after the Civil War. Pontil bases are an antebellum feature of bottles.
Look for an intact label. The label on a glass jar or bottle can increase the value of the bottle. It may also contain a date that will give you a clue as to the year of manufacture. Some items that are no longer manufactured, such as early Victorian medicines or soda fountain syrup bottles, can date the bottle as one that was made prior to the discontinuation of the contents.