How can I tell how old a glass bottle is?

 

 Bottle Dating

HOME: Bottle Dating

INTRODUCTION

This page and associated sub-pages allows a user to run an American produced utilitarian bottle or a significantly sized bottle fragment(s) through a series of questions based primarily on diagnostic physical, manufacturing related characteristics or features to determine the approximate manufacturing age range of the item.  As Berge (1980) noted in referring to bottles, the "...mode of manufacture of glass containers provides observable attributes which seem to be very useful in a classification of these artifacts."  Thus, this page.

This bottle dating "key" is a relatively simple "first cut" on the dating of a bottle.  While running a bottle through the key questions, the user is frequently directed to move to other website pages to explain diagnostic features and concepts as well as to add depth and/or precision to the initial dating estimate.  Please be aware that in order to gain the maximum information about any particular bottle (e.g., dating, typing) the user must usually review a number of pages within this website. 

Unfortunately, the complexities of precisely dating bottles is beyond the scope of any simple key; more complex keys are far in the future if they ever become available.  A substantial amount of bottle type specific information must be reviewed by a user to increase the probability of dating accuracy.  Additional reference materials outside of this website must usually be consulted to narrow down the date of any item as far as is possible and to really get a "feel" for the history of the bottle in question.  Additional reference materials include: bottle type or location specific bottle books and experts; period business directories; period newspapers, magazines and other printed publications; local, state or regional historical societies, museums, libraries, and colleges/universities; and others this author is forgetting. 

Fortunately, as each year passes more of this type information becomes available on the internet.  Since this website was initiated (2002) a simple search for a bottle can now yield much more information than back then, depending on the precision and wording of a search.  This admittedly can be very challenging with bottles that have no company, user, or bottle maker related embossing or original labeling.  The information on this website will, however, usually produce a reliable manufacturing date range for a majority of American utilitarian bottles manufactured from the late 17th century to the mid-20th century.
 

Click here to move directly to the "Dating a Bottle" Section below.

For the first time user of this site it is highly recommended that
 the following information be read prior to using the key below.

Having stated the above, there are still many diagnostic features or characteristics that provide a high probability of both dating and typing a bottle with some precision.  The more datable diagnostic characteristics that can be used, the closer the date range can be narrowed and/or the more confidence one can have in the range determined. 

A key concept in historic bottle dating is the high probability (i.e., high likelihood) that the age range noted for a particular diagnostic characteristic is accurate for a given bottle which has that diagnostic feature.  The general probability estimates noted on this website are based on a merging of reliable references with empirical observations made by this site's affiliated consulting experts (see the About This Site page) and the author all of whom have been students of historic bottle dating and identification for many years.
 

 

Notes on embossing, labeling, and existing research

Raised embossing (and when present, paper labeling) on a bottle can frequently provide important details to refine the probable manufacturing date range if information exists for the company that either manufactured the bottle (i.e., glassmaker marks) or had the bottle made for them (i.e., the buyer & user of the finished bottle).  For example, the early San Francisco mineral water bottle pictured here is known to date between 1850-1851 based on the information provided by the embossing (company name embossed on the pictured side and the glass maker - Union Glass Works - embossed on the reverse) and research done by collectors (Markota 1994). 

Researched historical information of variable depth and quality exists for thousands of different - typically embossed - bottles.  Published works generally cover either a particular city, region, or category of bottles.  Quality examples of references within each of these three categories are, respectively, Gordon Pollard's (1993) book on Plattsburg, NY bottles (Bottles and Business in Plattsburgh, New York: 100 Years of Embossed Bottles As Historical Artifacts), John Thomas's (1974) book on Western American liquor flasks (Picnics, Coffins, Shoo-Flies), Alice Creswick's (1987) books on canning jars (The Fruit Jar Works - Volume 1 & 2) and David Burton's (2015) monumental 3 volume work on sealed bottles from around the world (Antique Sealed Bottles - 1640-1900).  See the References page for more information.

For a large majority of embossed and unembossed bottles, however, there is little or nothing formally published on the details of their origins.  There were many hundreds of  thousands of uniquely different bottles (including differences in the embossing on the same "type" bottle as well as different sizes) produced during the era covered by this website - 1800 to the 1950s - just in the United States.  Only a relative few geographic areas or areas of collecting interest have received more than cursory historical treatment and the majority of this is due to the efforts of collectors.

Unfortunately, it is likely that the majority of bottles produced during the 19th century have little or no information still existing today that would allow for substantive research.  Time has taken its toll on records, of course, but much of what happened in the past was simply not documented well or at all as with most endeavors of common people in the past.  As noted in Munsey's 1970 book, "When it comes to methods of dating bottles...history has not been very kind..."  Though much research has been done since Munsey's book, relatively little specific information exists about a large majority of bottles.  As Munsey also notes - "Most of what is used today to date bottles...is based on assumption and logic and at best is general" (Munsey 1970).  Still all true today.

All of the dating information on this site, including the following dating key, is based on the researched history and evolution of American glass making, specific glass maker histories, and the above noted regional research on specific - typically embossed - company/product bottles.  This body of information will be utilized and extrapolated to make dating (and typing) estimates for the majority of bottles for which there is either no specific company or glass maker information available or such is not possible to determine because the bottles are unmarked (i.e., not embossed) and are no longer labeled.  (Note: An excellent reference on the art & science of dating and identifying bottles based on a myriad of different information sources and type collections is found in Bill Lockhart's (2001(d)) article entitled "A New Twist for Uncapping Old Information about Glass Artifacts".)

Historical Archaeology journal article entitled A Dating Key For Post-Eighteenth Century Bottles by T. Stell Newman (Newman 1970).  Newman's key made a noble attempt at simplifying bottle dating, but is weakened by the fact that the subject is much too complex to be conducive to such a simple approach by itself.  Also, the format and space constraints of a journal article do not allow for the elaboration and illustrations necessary to make a key function fully (Jones 1971b).  Mr. Newman wryly recognized all this with his reworking of an old saying: "This bottle dating key is for the guidance of the wise and the obedience of fools."  (Note: A pdf copy of Newman's article is available courtesy of the SHA by clicking on the following link: 

To the authors knowledge, the first serious attempt at using a key to date American bottles was done in a 1970journal article entitledby T. Stell Newman (Newman 1970). Newman's key made a noble attempt at simplifying bottle dating, but is weakened by the fact that the subject is much too complex to be conducive to such a simple approach by itself. Also, the format and space constraints of a journal article do not allow for the elaboration and illustrations necessary to make a key function fully (Jones 1971b). Mr. Newman wryly recognized all this with his reworking of an old saying:." (Note: A pdf copy of Newman's article is available courtesy of the SHA by clicking on the following link: Newman 1970 .)

This website is designed to have the informational depth, pictures, and illustrations necessary to solve the problems of the Newman key though his warning still holds, although hopefully less so.  This entire website is essentially a key to the dating and typing of bottles. 

(Note:  Cecil Munsey's  exceptional 1970 book on general bottle collecting - The Illustrated Guide to Collecting Bottles - included a chapter on "Dating Bottles."  It did lack specificity in that it simply used a line chart to show the estimated range for various "Techniques, Tools, and Tool Marks" between 100 B.C. and 1970.  However, the author of this site still recommends Dr. Munsey's book as the best overall printed publication on the subject of bottle typology, bottle & glass production, and related subjects.  Though long out of print it is still widely available through internet used book sites, eBay®, and in used book stores.)

Before jumping into the key, it must again be emphasized that no single key can get a user to an absolutely precise date for any bottle.  The best the following key can do is get a user to a reliably close dating range estimate.  Other information on this website usually must be reviewed to fine tune the information about a specific bottle. 

In addition, other references beyond the scope of this website usually must be consulted to get as complete of a dating and typing story as is possible for any given bottle. This include period newspapers, business directories, glass makers catalogs, trade journals and related publications, and other sources too numerous to detail.

 

Keep this all in mind as you progress through the key which follows and on into the other website pages.............good luck!

 

The "DATING A BOTTLE" Process Starts Here!

Starting with Question #1, follow through the questions as suggested.  There is frequent hyper-linking between the diagnostic characteristics and terminology listed on this page and other website pages.  This is done to allow the user to get more information or clarification as they proceed through the key.  Pursue these links freely since they will take a user to more details on bottle dating and identification and hopefully add to the users knowledge and understanding about the bottle being "keying out."  When a dating sequence dead ends, it will be noted and other website pages suggested (and hyperlinked) for the user to consult.

The three questions found on this page below answer several basic questions about a given bottle.  Answers to these questions will then direct a user to one of the two additional dating pages which are extensions of this key for the two major classes of bottles: mouth-blown bottles and machine-made bottles. 

Read the questions - and accompanying explanations and exceptions - very carefully as the correct answer is critical to moving properly through the "key."

If you jump from this page to another for added information, use the Back arrow on your browser or the Dating page hyperlink in the navigation bar to return to this page, unless it is a Pop-Up page (a separate browser window) which would need to be closed ("x" in upper right corner) or minimized ("-" in the upper right).

For examples of how to use this dating key see the Examples of Dating Historic Bottles page.  This page guides a user through the key for seven different type and age bottles with several being side-by-side comparisons of very similar bottles of different eras.  This page also shows how other portions of this website can provide information pertinent to the bottle in question.

This dating key, as noted earlier, is based on a composite of information from many sources, as modified and/or expanded on with the empirical observations of the site author and other experienced individuals whom were consulted.  (See the About This Site page for more information about the author and contributors.)   The major References that support the construction of this key include Kendrick (1963 & 1968), Toulouse (1967, 1968, 1969b, 1970), Newman (1970), Munsey (1970), Jones (1971), McKearin & Wilson (1978), Zumwalt (1980), Miller & Sullivan (1981), Deiss (1981), Elliott & Gould (1988), Jones & Sullivan (1989), Boow (1991), Fike (1989 & 1998), Thomas (1974, 1998a & b, 2002), Miller & McNichol (2002), Smith (2003), Van den Bossche (2001), Farnsworth & Walthall (2011), Burton (2015), Lockhart (scores of publications & articles over many years) and hundreds of other sources to varying degrees.  For brevity, most of the specific references are not noted in the key's narratives.  They are noted on the other website pages which expand on the information summarized in the key.

 

As an aid to the sometimes complicated process of determining a likely date range for a given bottle, a Summary Guide to Dating Bottles (20 pages) with attached Bottle Dating Worksheet (5 pages) has been prepared as a separate PDF document (25 total pages) for printing out an using. 

The documents first section (first  20 pages) is a condensed version of the three webpages that make up the bottle dating questions "key" which begins with the three questions on this page listed below and continues on to the various questions on the Mouth-Blown Bottles Dating page or Machine-Made Bottles Dating page.  The document includes most of the same full color images found accompanying the questions on these bottle dating key webpages,  It also includes an easy (I hope) to follow and fill out Worksheet to guide a user.  This PDF document is basically the same as - and can be used in lieu of - the series of questions that begin below.  It, of course, can't link to the various bottle descriptive terms used in the questions which have frequent hot links opening up another window defining or describing the term. 

These dating question webpages used in hand with the Summary Guide/Worksheets are the recommended way to figure out the approximate date range of your bottle!  This document is available for downloading at the following link:
Summary Guide to Dating Bottles & Bottle Dating Worksheets

If you know your bottle is machine-made
click Machine-Made Bottles to move directly to that page.

If you know your bottle is mouth-blown (aka hand-made)
click Mouth-blown Bottles to move directly to that page.
 

 

QUESTION #1:  Does the bottle have raised embossing on the base, body, shoulder, and/or neck OR a distinct vertical side mold seam visible on the body, shoulder, and/or neck (or both features)?

If unsure about what embossing or vertical side mold seams (picture below) are, click on Bottle Morphology to see this sub-page for a illustration and explanation of these and many other key bottle related physical features.  Return back to this page by closing the Bottle Morphology page.  For expanded information on body mold seams and embossing review the Bottle Body Characteristics & Mold Seams page.
 

Vertical side mold seam on the neck of a beer bottle ending well below the finish, indicating that it was at least partially handmade - ca. 1905-1915.

YES - The bottle has embossing or visible vertical side mold seams somewhere on the body between the heel and the base of the finish or lip.  A bottle may have mold seams but no embossing, but all embossed bottles were molded in some way and have mold seams even if they are not readily apparent.  The majority of the bottles made in the 19th and virtually all in the 20th century were made in molds so "YES" is the most likely answer to this question.   If so, move to QUESTION #2 below.  (See note #2 below if there is embossing but it is only within a disk of glass which appears applied to the neck, shoulder or body of the bottle.)

NO - The bottle has NO embossing and NO apparent vertical side mold seams on the base, body, shoulder, or neck.  This bottle is either free-blown, "dip" molded, or was produced in a "turn-mold" (aka "paste-mold") where the side mold seams were erased during manufacture.  A "NO" answer is much less likely than "YES" for this question as a very large majority of bottles made during the 19th century and virtually all made during the 20th century were mold blown resulting in mold seams; see the notes below.  If you are sure that the answer is "NO", move to QUESTION #3  below. 

Notes:
1. A low probability though possible "NO" alternative is that the user has an unembossed, molded bottle with no visible vertical side mold seams.  This can be due to one or a combination of factors including post-molding hot glass "flow" masking the mold seams, fire polishing of the bottle body, or atypically good mold part(s) fitting precision.   If necessary, look very closely at the bottle shoulder - the best location to see vertical side seams on mouth-blown and most machine-made bottles - in good light with a hand lens to see if there is at least some faint evidence of where the mold part edges came together.  Often the vertical side mold seams are evidenced by very faint changes in glass density in lines where one would expect mold seams to be.  For additional help review the Bottle Body Characteristics & Mold Seams page.

2. If the embossing on a bottle is only within a separately applied blob seal similar to that shown to the right (click to enlarge), and found nowhere else on the bottle, the bottle is almost certainly mouth-blown.  Click QUESTION #4 to pursue more information on the Mouth-Blown Bottles portion of this key (you will move to another webpage).  This is another low probability choice but certainly possible.

 

 

Bottle DOES Have Vertical Side Mold Seams

QUESTION #2:  Do the vertical side mold seams go up to the highest vertical point of the finish (aka "lip") side and usually onto the finish rim* itself  AND the topmost surface of the finish (rim) is not visibly ground down, i.e., the bottle does not have a "ground lip/rim"?  (Also see the *Exceptions to Question #2 box below.) 

Dating Bottles with the
Side Mold Seam "Myth"

One of the longest running "myths" in the world of bottle dating is that the side mold seam can be read like a thermometer to determine the age of a bottle.  The concept is that the higher the side mold seam on the bottle the later it was made - at least in the era from the early to mid 19th century until the first few decades of the 20th century.  This dating tool was apparently devised by Grace Kendrick in her 1963 book "The Antique Bottle Collector."  This book was pioneering and reprinted many times into the 1970s and is probably the most common and widely quoted (by collectors and archaeologists alike) bottle book ever written, containing a wealth of generally good information. 

This concept was articulated by Kendrick's in a chapter entitled "The Applied Lip" which contains an "Age Gauge: Mold Seams of Bottles" chart (Figure 9).  Kendrick's explains in the text (pages 45-47) that...

It is true that the mold seams can be used like a thermometer to determine the approximate age of a bottle.  The closer to the top of the bottle the seams extend, the more recent was the production of the bottle.

The chart accompanying this statement notes that bottles made before 1860 have a side mold seam ending on the shoulder or low on the neck, between 1860 and 1880 the seam ends just below the finish, between 1880 and 1900 the seam ends within the finish just below the finish rim (top lip surface), and those made after 1900 have mold seams ending right at the top surface of the finish, i.e., rim (Kendrick 1963).

Although there are examples of bottles having mold seams that fit these date ranges properly, the issue of dating bottles is much more complicated than the simple reading of side mold seams.  If it were that simple much of this website would be unnecessary!  For example, the process that produces a tooled finish frequently erases traces of the side mold seam up to an inch below the base of the finish whereas the typical applied finish has the seam ending higher - right at the base of the finish (Lockhart et. al. 2005e).  The reason this is noted here is that the concept keeps popping up in the literature of bottle dating and identification ranging from Sellari's books (Sellari 1970:5) published shortly after Kendrick's book to as recent as Fike (1998:4) and Heetderk's (2002:15).  It is also frequently noted by sellers on eBay® when describing their offerings.  For a broader discussion of this subject see Lockhart, et al. (2005e) - Debunking the Myth of the Side Seam Thermometer

The issue of mold seams and dating is explored in various portions of this website, but in particular on the Bottle Body Characteristics & Mold Seams and Bottle Bases pages, with additional information found in various other locations. 

If unsure about what the lip, rim, or finish of a bottle is, check the Bottle Morphology sub-page.  See the ground rim/lip portion of the main Bottle Finishes & Closures page for a discussion of this feature.  If the bottle does have a ground down rim/lip go to the NO answer below.  If you need more information on this diagnostic feature - including various images - click the following link: Bottle Finishes & Closures: Part II - Types or Styles of Finishes
 

Close-up of the finish (lip) of an Illinois Glass Co. (Toledo, OH.) bottle manufactured on an Owens Bottle Machine - ca. 1915-1920.

YES - The vertical side mold seam or seams go to the highest vertical point of the finish side and (usually) onto the top surface (rim)* of the finish AND the top surface of the finish does not appear ground down. 

This is a "machine-made" bottle or jar and will also usually have a highly diagnostic horizontal mold seam just below the finish base that circles the neck.  This is especially obvious with narrow mouth or bore bottles but can be found on wide mouth/bore bottles also - like canning jars.  The picture to the left shows both of these mold seams (click to enlarge). 

Bottles with these diagnostic mold seams in evidence were made by either semi-automatic or fully automatic bottle machines and virtually always date after ~1900 (for wide mouth bottles and jars) and after ~1910 for narrow bore bottles (Miller & McNichol 2002).  Machine-made bottle making processes are described in much more depth on the Glassmaking & Glassmakers page.

If your bottle fits this description, click Machine-made Bottles to move to the related webpage which allows the user to pursue more information on bottles produced almost totally in the 20th century by some type of automatic or semi-automatic bottle machine.

NO - The top surface of the finish is either ground down (most commonly seen on canning/fruit jars but also on screw thread finish liquor flasks, ink bottles, perfume, and other types less frequently) or the side mold seam stops or fades out distinctly below the top of the finish and usually - but not always - below the lowest portion of the finish (i.e., collar) as shown in the Question #1 picture above.  (See the *Exceptions to Question #2 box below for several significant exceptions to the side mold seam "rule.")

Bottles with this discontinuous or fading vertical side mold seams are referred to as "mouth-blown" or "hand-made" and typically date prior to 1915, though could date back to at least 1800.  The vast majority of U. S. manufactured, mouth-blown molded bottles were made between about 1820 and 1915.  Click QUESTION #4 to pursue more information on the Mouth-Blown Bottles portion of this key (you will move to another webpage).  If your bottle has a ground rim or lip, more information can be found at the following link: Bottle Finishes & Closures: Part II - Types or Styles of Finishes
 

 

Bottle DOES NOT Have Vertical Side Mold Seams.

QUESTION #3:  Is the bottle cylindrical/round, exhibiting very symmetrical conformation, and with the body and/or neck having faint concentric "rings" or striations on the glass surface going horizontally around the body of the bottle as shown in the picture below?

The concentric rings are not always as obvious as the picture shows (click to enlarge) and sometimes not visible, though if present it is a conclusive diagnostic feature.
 

Turn-mold bottle body showing faint concentric rings.  "Hock" wine - ca. 1890-1915.

YES - This bottle was produced in a turn-mold which was also known in the glass industry as a paste-mold.  All turn-mold bottles are cylindrical and unless stained, will usually have a polished looking sheen to the glass surface. The large majority of turn-mold bottles date between 1880 and 1915, though they were produced as early as the mid-1850s and as late as the early 1920s (Switzer 1974; Deiss 1981; Jones & Sullivan 1989; Boow 1991; Gerth 2006; empirical observations). 

A "YES" answer to this question is more likely than a "NO".   Go to QUESTION #5 for a possible dating refinement based on the method of finish application, though some of the diagnostic features can be masked by the turn-mold production process.  For more information on turn/paste mold bottles consult the Bottle Body Characteristics & Mold Seams page.
 

NO - The bottle is either not cylindrical, or if so, is very crudely made and non-symmetrical exhibiting no concentric body/neck rings.  This bottle is mouth-blown and likely either free-blown or dip molded.  These two manufacturing types can be hard to differentiate from each other, though free-blown bottles are usually cylindrical or oval in cross-section and have lines that are not sharp (i.e., a "flowing" look).  Most free-blown bottle date prior to the 1850s though can be much older as this method was used at least as early as Roman times.  Dip mold produced bottles are either cylindrical, square or rectangular in the body but usually have more distinct lines from the lower shoulder down since most if not all of the body was actually molded (Jones & Sullivan 1989).  Dip mold bottles usually date prior to 1865-1870 but can also be much older (back to early 18th century at least). 

A user may move to QUESTION #4 for one additional dating attribute based on pontil scars, though all these datable attributes (free-blown, dip mold, and pontil scars) overlap significantly.  Consult Bottle Body Characteristics & Mold Seams page for more information on and images of these type bottles.

Note:  All turn/paste mold, free-blown, and dip molded bottles are also mouth-blown or hand made bottles, which is covered more on the Mouth-blown bottle dating page (link below).

 

 

Click Mouth-blown Bottles to move to the portion of the Dating key for Mouth-blown bottles
(new webpage).

Click Machine-made Bottles  to move to the portion of the Dating key for Machine-made bottles
(new webpage).

 

SEARCHING THIS WEBSITE: 
To do a word/phrase or image search of this website one must use the following Google search link: 
Search the SHA/BLM Historic Glass Bottle Identification & Information Website 
(Note: Search results for this website will be just below the final top-of-the-page Google paid ads.)

1/1/2024

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This website created and managed by:
Bill Lindsey
Bureau of Land Management (retired) - Klamath Falls, Oregon
Questions?  See FAQ #21.

Copyright © 2024 Bill Lindsey.  All rights reserved. Viewers are encouraged, for personal or classroom use, to download limited copies of posted material.  No material may be copied for commercial purposes. Author reserves the right to update this information as appropriate.

Estimating the age of antique bottles can sometimes be a difficult task even for the experienced collector. However, by following some basic guidelines anyone can determine approximate age. Although this brief article is primarily intended for American-made bottles, glass from other countries has evolved similarly. This outline covers basic patterns but note that there are exceptions to every rule.

Mold Seam

Most bottles produced in the past 150 years were formed by blowing molten glass into a mold. Molds were made of iron or wood and consist of 2 or 3 pieces. When the bottle was removed from a mold, a faint seam remained in the glass, running from the base to a point somewhere between the shoulder on up to the top edge of the mouth. In a 3-piece mold, a seam often runs horizontally around the shoulder of the bottle with opposing seams on the neck.

To some extent, the height of the mold seam on the bottle can indicate age. However, there are plenty of exceptions to any kind of “thermometer” rule (ie. the higher the seam goes, the newer the bottle.)

Entire classes of bottles break the rule. For example, fruit jars made in the third and forth quarters of the 19th century. Sheared top bottles are another case where mold seam height is not a good indicator of age.

See the Mold Seam Examples page for more details [coming soon]

Base of Bottle

Pontil mark – A iron rod was often stuck to the base of hand blown bottles prior to approximately 1860. This allowed an assistant to hold the bottle while a glassblower would attach and finish the lip of the vessel. When the bottle was broken or sheared, a ring or area of rough glass or grey graphite remained. The pontil is a definitive mark that dates glass. Be aware that reproductions can have smooth, molded pontil marks or sometimes an authentic looking jagged mark.

Numbers and Letters- Such markings on the base indicate late 19th century to present time day manufacture. Occasionally, you will see base embossing of patent dates or the classic Rickets Patent of mid-19th century era.

Wheaton – Indicates glass made at the Wheaton Glassworks in southern New Jersey. This company was prolific in its production of reproduction and other antique-looking bottles and glass which they produced in the mid 20th century to the present.

CB – Stands for Clevenger Brothers, glassblowers also from New Jersey who produced high-quality reproduction glass. Owens bottle ring- During the period of 1890 to 1910, Micheal Owens developed automated methods for opening and closing bottle molds which led to mass production of glass and bottles. A distinctive characteristic of wares made by this method is a thin embossed circle on the base of the bottle, usually found with numbers and other marks indicating year of manufacture, mold number, etc. Bottles with such markings date from approximately 1910 to 1960

Other Guidelines

Specific embossing found on bottles can be an immediate indication of age. Liquor bottles produced after Prohibition (after 1930) are found with the embossing “Federal Law Prohibits Sale or Reuse of this Bottle.” Bottles marked “Wheaton” on the base are probably reproductions made by Wheaton Glassworks in New Jersey in the 20th century. Other common markings include “W.T. Co.” which stands for Whitall Tatum, a turn of the century glass manufacturer. An entire book called Bottle Makers and Their Marks by Toulouse documents the hundreds of markings made by glass manufacturers.

Reproductions

Don’t assume that the old bottle you have is necessarily old or antique. There are a lot of reproduction bottles out there, and new ones that look old are made every day. Modern bottles are sometimes intentionally made to look old and mimic the shape, surface texture and overall appearance of hand blown glass.
Be wary of bottles that have dates on them such as 1776 or others prior to 1850, since dated bottles prior to this time are rare. Bold and garish colors are also rare in antique bottles, so beware of bright reds, greens, yellows and purples. If it looks too good to be true, it probably is!
Bottles that are made to look old often are exaggerated in their “handmadeness”. There are huge numbers of bubbles and impurities in the glass. The glass itself is commonly thick, heavy and distorted in shape. Early glassmakers tried their best to make uniform, quality wares; modern makers try hard to make their bottles look handblown.

Mouth of Bottle

Perhaps the most obvious key to age is the mouth of the bottle. As a general rule, screw top bottles (except canning jars) were made after 1910 or so. Cork top bottles generally vanished at the turn of this century. Look closely at the mold seam and where the lip meets the bottle. All truely hand blown bottles have an applied lip. The curious student of glass items will quickly learn when a lip has been formed onto the bottle and when it was applied by hand. Handwork in glassblowing disappeared in the late 19th century. It is a safe rule that after 1890, few, if any, bottles were mass-produced with an applied lip.

There’s no substitute for experience

Take some time to talk with a bottle collector at a local club or show. Examine as many old bottles as you can and ask lots of questions. You will find that you can quickly train your eye to know a lot about the age of most bottles that you will find.

Got A Question about Your Bottle?

Ask it on our Discussion forum