Dating antique bottles requires knowledge of the evolution of bottle technology and the ability to research manufacturers and bottling companies. Although glass bottles have been made for a few thousand years, it was not until the 19th century that bottle use became common, coinciding with the industrial revolution. By the midth century, embossed lettering and marking on bottle bodies and bases, denoting manufacturers and products, made more precise dating possible. In addition to technology, products and manufacturers, certain types of glass colors will also aid in dating. Look for mold seams. The earliest bottles were hand-blown by a glassblower with a blowpipe and lack seams.
However, the process of bottle identification and dating is quite complex with many exceptions; thus, the need for many web pages covering an extensive amount of descriptive information. A listing or "map" of all the main subject pages and connected sub-pages found within this website is found at the following link - Website Map. Use that page to get a feel for the structure of this website and to access any of the other web pages. It is suggested that if you only bookmark one page of this website for future reference, that it be the Website Map.
That page also includes a summary of significant recent changes and additions to this website. When possible, the information on this website is given general reliability rating estimates e. It is recommended that a new user first view a short listing of User Tips about how this site "works.
It does not attempt to fully address the dating of "specialty" or imported bottles made during that time, though much of the information found on this website is pertinent to these items to varying degrees. What is a utilitarian bottle or jar? What are specialty bottles? Both are hard questions to answer and the answer is somewhat arbitrary in the end.
For this website the distinction between the two categories is related to the varying time frames that different glass making techniques were used for the two classes of bottles. Click on utilitarian bottles or specialty bottles to view the portion of the Glossary Page that covers these subjects.
The author has tried to define the distinction between these two classes of bottles from the perspective of the intent of and information found on this website. Empirical observations indicate that Canadian-made bottles very often followed similar glassmaking technique and process chronologies making much of the information applicable to Canadian made bottles.
If using this site for the dating or typing of a known or likely Canadian-made bottle, keep this in mind as the reliability of the information may be reduced. Notice also how unlike most pontil marks, the Owens ring covers the whole base of this bottle. The base of the second bottle whose lip was shown above right is displayed here. The the lower left corner you can see evidence of the diagonal mold seam which at one time bisected the base. The Owens ring again covers the entire base and even intrudes out to the side of the bottle slightly.
In the center of the Owens Ring the Owens mark is shown the diamond. Owens rapidly made improvements as eh redesigned his machine numerous times and eventually over came the problems of uniformity see here.
All of the bottle mouths shown below were machine made. In the s, the bottle mimicked early forms which were hand tooled and sealed with a cork. The automatic bottle machine was much more precise in gathering an exact amount of glass and the same amount of glass for each bottle this consistency lead to more uniform products. With the uniformity, came the possibility to create a solid seal with a screw cap. Slowly the corked top bottle began to disappear in favor of the screw top.
The food and household product industries on the other hand widely adopted the screw cap quickly. One unique closure to the late s was a three point screw top. Sometimes the excess slop-over is not evident or the finishing glass application was inadequate in quantity resulting in a finish that is "missing" some portions.
In general, the appearance of an applied finish is less vertically and sometimes horizontally symmetrical than a tooled finish. Note: this ridge is not visible in the picture but can be very distinctly felt on the bottle and is shown in the illustration below - click for larger illustration with the applied finish attributes pointed out.
Click HERE to see a picture of an applied finish where this interface is visually evident in the middle of the finish. If visible, concentric horizontal tooling marks from a finishing tool will be present on the finish itself but not on the upper neck just below the finish.
Virtually all applied finishes outside of some "laid-on ring" types discussed earlier had to be hand tooled after the glass application in order to achieve the desired shape.
The rotation of the finishing tool very often left its mark on the finish in a similar fashion to those on tooled finishes though tooled finishes covered next also have the tooling marks extending onto the upper neck immediately below the bottom of the finish with the side mold seams disappearing at the base of those tooling marks.
This feature is unusual, though not unknown, on tooled finishes and can be quite indicative of the presence of an applied finish. This feature is the result of the difference in temperatures between the applied finishing glass hot from the glass pot and the slightly cooler glass of the upper neck, which would have cooled a bit after being cracked-off the blowpipe.
A combination of features aband d are the most commonly found visible features, with c being felt frequently if a finger will fit in the bore. Sometimes a very well executed applied finish "neatly applied" in collector jargon will only show the side mold seam disappearing at the base of the finish a with maybe some faint tooling marks on the finish itself d but not the extreme upper neck.
The specific dating of bottles with applied finishes is covered after the next section, as the dating of the transition from applied finishes to tooled finishes is somewhat bottle type specific. But before that subject can be covered the "tooled" finishing method must be discussed next. Tooled finishes. See "Important Note" below. To the below left is an image of a typical tool used for tooled finish forming that dates from between about and More information on this tool is found a bit further down the page.
It was inserted in the neck of the bottle and rotated or the bottle rotated with the snap tool while squeezing the jaws to form the finish to the desired conformation. It should be noted that this conformation of finishing tool may have been used for the final forming of either tooled or applied finishes.
Click Patent No. Patent Office b. Tooled finishes are also called "wiped" finishes by some - a fairly descriptive term for the process Preble ; Fike Instead, the term "tooled finish" as used on this website refers to the more distinctive finishes fully formed from non-added glass by use of finishing tools like that pictured to the left and illustrated at the link in the above paragraph. This is a fine distinction, but has important ramifications to the proper dating of bottles.
This glass would have then been substantially re-fired in the glory-hole and tooled to the desired shape with all evidence of the applied glass masked by the combination of re-firing and tooling.
How these bottles would be differentiated from the regular tooled finishes formed without added glass as described here is unknown and likely can not be. In any event, the identification and dating information described here would still be pertinent to these bottles which exhibit "tooled finish" diagnostic characteristics [Toulouse b].
The patent illustration shown to the right is from an patent for a "Finishing-tool for Glass Bottles" which was patented by Thomas K. This tool was clearly designed to form "tooled finishes" as described above and as used on this website, i.
The patent narrative states the following about the tools use, which includes a great general description of the tooled finish type creation process:. The manner of operating our device is as follows: The bottles, which have been completed, and whose necks, mouths and extensions it is desired to finish, are heated to such an extent that the necks become soft and plastic to a degree as to be readily formed or molded in any desired shape. The spindle of the finishing tool is then inserted in the mouth of the bottle, and the spring jaws gradually closed until the finishing dies Authors note: The finishing dies are the part of the tool that is shown in the illustration to the left encasing the finish of the bottle.
At the same time the bottle is turned, the dies operating on the outside of the bottle neck, and gradually bringing it in the shape of the dies After the end of the bottle has been finished off as mentioned, by releasing the pressure of the spring jaws Click Patent- Finishing-Tool for Glass Bottles - July 4, to view this entire patent including the narrative section which explains the construction and use of this finishing tool.
Below is an excerpt from a U. Continued blowing after the glass has taken the shape of the mold causes the glass above the top of the mold to break.
After the mold has been opened and the bottle removed, a snapper-up seizes it with a pair of pincers and places it neck upward in a "snap," a sheet-iron can with an iron handle about 3 feet long, which is of the same size and shape as the bottle. The snapper up rubs the jagged neck of the bottle on a piece of sheet iron and then inserts the bottle, still in the snap, into the "glory hole," or reheating furnace, the neck of the bottle just touching the flame.
When the neck has been heated sufficiently to make it workable, the bottle is taken out of the glory hole. With his left hand the finisher rolls the handle of the snap on the horizontal arm of his bench, and with his right hand he finishes the neck of the bottle by means of a tool, one part of which, inserted in the neck, opens it out and the other part, a pair of hinged jaws, makes the lip as the bottle is turned.
Three men, constituting "a shop," usually work together, two of them gathering the glass and blowing the bottle and the third finishing the neck.
The three may interchangeably perform these operations. Palmer et al. Empirical observations by the author indicate that there were two distinct variations of the tooled finish based on mold conformation and finishing activity - the "standard" and the "improved" tooled finishes - both of which can be accurately referred to as "tooled finishes. These types are described as follow:. This simple and generally oldest tooled finishing method entailed a mold where the finish conformation was not significantly pre-formed in the mold.
The shape of the base, body, and neck of the bottle were formed by the mold, but not the precise shape of the finish. To put it differently, there was limited or none or can't be determined pre-forming of the finish by the mold itself as the finishing tool was utilized to completely form the finish conformation.
Although the earliest of the two tooling methods, it also continued in used up until being replaced by machine-made methods, overlapping the "improved" tooling method described next.
The "standard" tooled finish is identified by a side mold seam that distinctly ends or fades out on the neck distinctly below the bottom edge of the finish.
This is illustrated by the images to the above left and to the right click both to enlarge. Click two-piece post-bottom mold to see an illustration of a typical bottle mold. This illustration shows that the upper neck portion of the mold does not accomplish any molding of the finish shape, just the neck shape. This type mold could have produced a bottle finished with either an applied finish using glass applied to the neck end which was tooled or a tooled finish by re-heating and compression tooling the end of the straight neck without additional glass added.
Click on Patent No. Wilson in U. This particular tool conformation, as the patent name notes, was designed to tool both the finish and the upper neck of bottle producing a "standard" tooled finish where the upper portion of the neck as well as the finish would exhibit horizontal compression tooling marks. The original iron finishing tool shown earlier in this section to the above left is clearly one that would have produced a "standard" tooled finish as the jaws extend well beyond the base of the finish and would likely have left evidence of their use on the upper neck of the bottles it was used on.
This particular tool is a larger than average example designed for the oversize finishes on demijohns and carboys. The middle image shows the tool with the jaws clamped shut in the finish forming position.
Dating antique ink bottles
The middle image clearly shows the conformation of the intended finish as the open space between the jaws and the central plug - a finish which would have resembled that in the image to the right below.
The "standard" tooled finish could be considered a transition type tooled finish that was easily adapted to bottles produced in molds that were previously finished with an applied finish.
These two bottles are also date estimated and discussed at length in the section below entitled A Mouth-blown Finish Related Dating Example. Later bottle molds produced with the intention of using the "standard" tooled finishing method were almost certainly made with a slightly longer neck in order to provide adequate glass for the process.
The following quote is from a publication National Glass Budget indicating such along with a reference to the former method of producing applied finishes:. Formerly the bottle lip was finished by laying on a thread of hot glass, and each blower finished his own bottle. This method of finishing was slow, and required skill and strength of arm, so that when the neck was lengthened and the bottle finished at the glory hole by stoving back the reheated neck so as to form the ring, it increased the output, and made the work lighter.
Anonymous ; emphasis added. Towards the later end of the mouth-blown era late s through the s many molds did significantly pre-form most or all of the basic external finish shape, i. Kendrick called this type mold a "closed" mold as versus an "open" mold which did not form any of the actual finish conformation Kendrick Bottles produced in this latter mold could be finished with either an applied or standard tooled finish, as described above.
The improved tooled finish is identified by a side mold seam that ends or fades out well into the conformation of the finish itself, often just short of the rim of the finish. Click catsup threaded improved tooled finish to view an example which would have been formed by a mold similar that illustrated below. The concentric tooling marks are evident only in the upper portions of the finish.
Sometimes these tooling marks are vague or non-existent, indicating that at times the upper finish was simply refired after removal from the blow-pipe or re-fired after the tooling to smooth the finish.
These type finishes were definitely not formed by added glass and strongly indicative that the vast majority of tooled finishes of both types - "standard" and "improved" - were not formed via the addition of added glass. The illustration to the left shows a "cup-bottom" closed mold which has the conformation of the external screw thread finish incorporated into the mold itself, i. This mold type is also referred sometimes to as a blow-over mold.
One of these processes would have had to be done to make the upper finish suitably smooth and consistent enough to reliably seal with a screw cap. The picture to the right click to enlarge shows the type of finish on a ca.
It is mouth-blown with molded external threads which also exhibits tooling marks in the finish area above the top of the screw threads. A bottle with this type of external screw thread finish almost certainly dates from the era; this type finish was used frequently on later mouth-blown liquor flasks like that pictured as well as some other types of bottles, particularly those intended for catsup.
Click external screw cap to view the discussion of mouth-blown external screw thread finishes and caps on the "Types of Bottle Closures" page. Click on the following link - true applied external screw cap finish - for a discussion of a very unusual true applied finish with external screw threads - an extremely uncommon occurrence. The picture below click to enlarge shows the "improved" tooled finish characteristics close-up. The location of the seam on this bottle makes it readily apparent that the basic finish form, including the lower ring, was formed by the mold without the addition of added glass.
The "improved" finish almost always identifies a bottle as having been produced after empirical observations. Almost certainly the first important, fully molded glass container finish was in with the invention and production of the Mason canning jar Deiss These revolutionary jars were produced from a blow-over mold where the outside screw thread finish was molded along with the body and base. The rough cracked-off top surface of this finish subsequently ground off to make it uniform and flat ground finishes are covered in Part II.
In general, with the exception of simple straight finishes simply sheared or cracked-off upper neck ends which were mold-formed and canning jars, bottle molds with incorporated finishes in whole or in part were little used until the late s, receiving only limited use until the s when they became fairly common until machine manufacture dominated the bottle making world in the mid to late s Deiss ; empirical observations.
Additional Tooled Finish Information. Due to the amount of tooling on most bottles produced with this finishing method, the upper side mold seam is often substantially "wiped out" making it difficult to determine how much shape forming the finish received in the mold versus how much was purely from the tooling actions. All though just a speculation by the author, it is quite possible that many tooled-finishes-to-be had at least the basic finish conformation formed in the mold as that would have been an easy way to provide the proper quantity of glass in the correct area for adequate finish completion.
The subsequent re-firing and finishing tool action to "finish" the finish eradicated most or all of the signs of the side mold seam for as far as the tool reached on the outside of the neck. The absence of the mold seam in the finish itself likely makes many "improved" tooled finishes actually appear to be "standard" tooled finishes. In other words, if the mold seam is evident within the finish, one knows that it is an improved" tooled finish; if the side mold seam is not evident in the finish then one can't say for sure that it was not partially molded, only that physically it is a tooled finish.
This is belaboring a fine point, but it does have dating implications. To picture the difference in these finish classes another way, the blowpipe detachment point on an applied finish was at or just above the point where the finish and neck meet in the finished bottle; the blowpipe detachment point on tooled finishes was or became the top surface of the finish.
Besides the labor savings, the tooled finish was a major innovation in that the bore and upper neck of bottle could be made more smooth, properly tapered, and of uniform dimensions as compared to the applied finish.
This allowed for more reliable sealing of the bottle with a cork in particular since more of the inside surface of the finish was in contact with the cork Deiss pers. Tools specifically for finishing were developed around in England and around in America. These devices usually consisted of a rod, which was inserted into the mouth of the bottle, and an associated part that could be clamped to the outside of the mouth and neck.
By rotating the device the lip was finished and the seams erased. Later these specific lip finishing devices were attached to workbenches and operated by hand- or foot-operated presses. If the bottle thus finished was rotated during the process the side seams were rubbed out but if the bottle was merely pressed the side seams were left intact and ran all the way to the top of the bottle.
These processes described by Munsey would be applicable to both applied and tooled finishes, though it is likely that the workbench operated finishing would have been much more common on the later tooled finishes. Beginning in the s many versions of these bench-operated, rotating pressing tools were patented possibly indicating that the changeover period to tooled finishing was peaking.
These relatively simple, hand or foot operated finishing "machines" clamped onto the finish and upper neck areas and generally erased the side mold seams anywhere the tool made contact with the glass Toulouse b.
Click Scheidt's May 17, Patentto see this machine. This patent's narrative noted that " The object of the invention is to provide a simple machine both in construction and operation and by means of which the bottle-necks may be quickly and accurately formed with unskilled labor " - a reference to the never ending pursuit of efficiency and cost reductions in the production of bottles U.
Patent Office a. On this website this class of finishes will be simply referred to as "tooled" finishes, with the distinction between the "standard" and "improved" versions made when useful. In the existing literature this finishing method is sometimes referred to descriptively as a "wiped" finish, presumably because the finishing tool "wipes" out traces of the upper side mold seams Preble ;Fike The side mold seam distinctly fades out on the neck of the bottle usually below the bottom of the finish shown in picture to the left.
Frequently, with later mouth-blown bottles early 20th centurythe side seam will disappear within the confines of the finish itself see the previous "improved" tooled finish pictures - above left and rightthough it will virtually never touch the outside edge of the top surface of the finish unless there is a ground finish rim.
Inkwell Collection L.B.M Co help bottle digging
Note: There are some machine-made milk bottles that have disappearing upper side mold seams that, upon first appearance, appear to have tooled finishes. This is discussed in the machine-made bottle finishes diagnostic attributes section below. The terminal end of the side seams on a tooled bottle will often bend slightly in the direction that the finishing tool was rotated.
Dating antique bottles requires knowledge of the evolution of bottle technology and the ability to research manufacturers and bottling companies. Although glass bottles have been made for a few thousand years, it was not until the 19th century that bottle use became . DATING BOTTLES BY THEIR TOPS AND BASES. A Look at Bottle Bases. One approach to helping beginner identify their old bottles involves show them the bases of old bottles. The picture below at the left shows an iron pontil on the base jof a historical flask circa The middle picture shows an open pontil on the base of a cylindrical medicine. Historic Glass Bottle Identification & Information Website: Main Subject Pages: Also linked to the Dating page is a sub-page called Examples of Dating Historic Bottles which tracks a few different bottles through a dating and general information quest to illustrate how the dating process and this website work.
This could be a function of either the gaffer being left or right handed or of how the workbench mounted finishing devices rotated under hand or foot power, as noted in Munsey above.
The difference could also be related to whether the tool rotated around a stationary bottle, or the bottle rotated on a stationary tool.
There appears to be no dating or glassmaker specific relevance to this feature; just an item of bottle making interest. Concentric horizontal tooling marks are usually present on both the finish and the upper portion of the neck above where the side mold seam fades or disappears rings show slightly in the picture.
Sometimes the side mold seams can be observed faintly "underneath" or within the tooling marks or rings. The side mold seam can also occasionally proceed faintly almost all the way to the top of the finish. This residual side mold seam s is likely a result of the glass beginning to cool and solidify while being hand tooled, allowing mold seam traces to remain in the finish. The presence of the side mold seam in the finish itself of a mouth-blown bottle positively identifies the finish glass as having been mold blown and not applied.
The absence of a line or ridge inside the finish - as would be found on an applied finish - since there was no separate application of finishing glass. When viewing the upper neck and finish from the side, there is often a visible change in the thickness of the glass on each side of the bottle neck in the vicinity of where the side mold seam disappears and the tooling marks begin. Often this is just a subtle smooth "hump" on the inside surface of the glass where the tip of the finishing tool ended.
However, some tooled finishes as described here date back to the s, but primarily with just certain classes of bottles e.
This is discussed in the next section. All hand tooled finishes largely disappeared between and the early s with the ever increasing dominance of semi-automatic and then fully automatic bottle making machines. Dating notes on the changeover period from applied finishes to tooled finishes: The changeover from applied finishes to tooled finishes was a relatively significant technological shift in bottle manufacturing.
This changeover can often provide a useful dating break for bottles made during the last quarter of the 19th century. As noted on the Bottle Dating page there was a lot of time variation in making this transition depending on the type or class of bottle. There were also variations based on different glass makers, but these are extremely difficult or impossible to track down as most bottles can not be firmly attributed to a particular glass factory during this era.
Empirical observations indicate that the mid s is when the transition from applied finishes to the more technologically advanced tooled finishes significantly commenced. There are a relatively limited percentage of bottles known to pre-date the mids that have the tooled finish as defined above. Those that are known are primarily smaller bottles discussed more below. Likewise, by the mids the changeover to tooled finishes was largely complete and a very large majority of American-made bottles dating after that time have tooled finishes.
The following information darker tan box below provides some general dating guidelines for this transition categorized by broad types or classes of bottles. It is based on the content managers extensive empirical observations over time in conjunction with an wide array of published references noted below the box which provide relatively precise company dating for various types and styles of historic bottles. As there are many exceptions to these general observations, specific bottle dating accuracy can only be achieved by using these finish related date ranges in conjunction with other diagnostic features as noted on the Bottle Dating pages.
Be aware that the information found below is a brief synopsis of the bottle type specific date ranges for the changeover from applied to tooled finishes.
See the Important Note listed earlier relative to tooled finishes formed by more technologically advanced finishing tools vs. As a general statement about the transition from applied to tooled finishes, it is clear that the smaller the bottle the earlier that tooled finishes were first used. Conversely, the larger the bottle up to around " in height the later that tooled finishes seem to have been adopted.
The total transition time from applied to tooled finishes is largely from the mids to the mids in the U.
Bottle Typing/Diagnostic Shapes: "Household Bottles (non-food related)" page Organization & Structure. This Household Bottles (non-food related) page is divided into the following categories and sub-categories based largely on the different contents that each group held, and within those groups, by various dominant shapes or other logical categories. To aid beginning collectors and those interested in bottles I have developed a number of bottle time lines. These diagrams should help clarify age differences based on both form and function. With each chart the reader will find accompanying pictures to further aid in bottle . Dating Antique Bottles. Many people are intrigued to know how old their bottle is. There are three keys to help with dating most bottles: Side seams: None: bottle may be free blown, in which case it has a very uneven shape and dates before Or the bottle may have a nice even shape, but was spun in the mold to smooth out the seams; a.
Why smaller bottles were tooled sooner than larger bottles is not known though the trend is very evident in the observation of tens of thousands of bottles by the author. It is, however, certainly related to the specific manufacturing efficiencies inherent in the methods of production for different bottle sizes.
Note on European Bottles. European made mouth-blown bottles tended to have "true" applied finishes much later than American made bottles, i. For example, the crudely applied oil finish pictured to the right is on a Dutch-made gin bottle that bears a label identifying it as having been made no earlier than when an elephant became the trademark for H.
Melchers - the Schiedam company that used this bottle Vermeulen ; Vermeulen pers. This bottle also has additional body crudity to it wavy bubble laden glass that would diagnostically place it from the s to s if actually made in the U.
Antique Ink Bottles
Click the following links for more images of this Dutch gin bottle: base view cup-bottom mold ; view of the label and the trade mark elephant ; view of the embossing. Photos courtesy of Ed Stephens. For example, there are an assortment of cylinder liquor bottles made for Western American companies that have the diagnostic characteristics of similar American made bottles from the s or early s, though they were actually made in Germany as late as the early s Thomas Another commonly observed, foreign made bottle with an applied finish are round bottom soda bottles with a crown finish!
The image to the right shows the finish on such a bottle; click full bottle view to see the entire bottle.
OLD BOTTLE IDENTIFICATION AND DATING GUIDE. This webpage is intended to help novice collectors and non-collectors better identify, describe, and date the bottles they encounter. Bottle dating is approximate and just intended to give a relative placement in bottle making history. 3. Ink/shoe polish bottles - Another common exception to this dating question deals with small ink bottles and similar small, moderately wide bore (mouth) bottles like shoe polish made during the . Links to other sites about Ink bottles: Ink Bottle Hall of Fame, which has been divided into Inkwells and Masters. Ink Bottle Books For Sale. Reggie's Antique Ink Bottles. Rob Goodacre's Ink bottles. Ink Bottle Collection of Emmett Baker, Email: [email protected] Ink Bottle Basics is an informative page on inks by Digger Oddell.
Note the glass "slop over" underneath the base of the finish onto the upper neck. The author of this website has received many questions about these soda bottles as they do not fit the applied finish dating "rules" described on this site. The crown finish was not invented untilwhich is after the vast majority of U.
DETERMINING THE AGE OF OLD BOTTLES
The author believes that virtually ALL of these applied crown finish bottles were made in the United Kingdom or elsewhere in Europe between possibly very late s to the late s or possibly early s.
Many were imported into the U. Smaller proprietary druggist and drug store bottles appear to have almost completely made the changeover to tooled finishes by the late s.
Prior to the mids druggist bottles tended to either have either a distinct applied finish or the older thin flared finish described earlier on this page; these latter bottles are also often pontiled scarred Davis ; Deiss pers.
This example has a tooled finish, no mold air venting, and is known to date from based on the short partnership period of the proprietors based on information gleaned by the author from period Portland, OR. Medicinals in the " tall "transition" range can have tooled finishes as early as the mids and applied ones as late as about empirical observations.
Larger capacity beer bottles 26 oz. These types are some of the latest American made bottles to commonly incorporate applied finishes. Occasionally, some bottles within these types are observed that are known to date after and have applied finishes; these are most likely imported bottles, as discussed above empirical observations.
Any type of bottle exhibiting the features of the "improved" tooled finish described earlier side mold seam evident within the finish itself; see image to the leftand which does not have molded external screw threads with a ground rim, will virtually always post-date and most likely dates between and the end of the mouth-blown era in the early s empirical observations.
Not all mouth-blown bottles from the era have the "improved" tooled finish, but virtually all bottles with this finish manufacturing variation are from the early 20th century.
Once again, it must be noted that the information above is a brief synopsis of the bottle type specific date ranges for changeover from applied to tooled finishes. This is evidenced under close inspection by both having identical embossing details from the mold embossing engraving and identical mold surface irregularities iron casting roughness.
Upon casual observation we can also reasonably conclude that these bottles were blown at separate times simply based on the color differences - they were likely blown from different batches of glass. Upon closer inspection we note that the bottle on the right has an crudely applied finish and the bottle on the left has a neatly tooled finish - see the finish close-up picture below click to enlarge.
The only other difference between the two bottles are some subtle differences in the bases of each indicating that the post-bottom mold plate was modified or replaced at some point in the molds life. The distance and transportation costs involved with bringing in bottles from the nearest glassworks at the time in the Midwest were usually prohibitive, giving the local glass maker an edge in the competition. This gives us our first broad dating sideboard.
We can also somewhat reliably date the mold to the first half of the s based on the distinctive "blob" style of a mold air-venting mark on the front shoulder; the back shoulder has the more typical pin-head type.
Click "Blob" Type Air Venting for view a close-up picture of this unusual venting method. According to Thomasthis style was estimated to be used during a narrow time frame of about to Since this was an estimate and molds were often used for some years, we could reasonably expand our dating estimate time frame a couple years on each end to increase the odds of being more correct - say to The apparent mold base plate modifications or replacement also supports a lengthy life span for the mold.
Since we have both tooled and applied finishes on a bottle with this type air venting, and given the information we determined above, it is reasonable to estimate that the example with the applied finish right dates from about and the tooled example from about Further research finds a few more facts to consider in our investigation these bottles. Our determined date range for these bottles superficially fits this information well.
However, there is much more to this story Though the rationales above seem to indicate a clear dating range, there are several other factors which must be considered as a note of warning to users on the complexities and inconsistencies of bottle dating. Unfortunately the authors usually did not provide specific rationales for their dating ranges and did not for the Peruvian Bitters.