Bottles and ExtrasFall 200514

Debunking the Myth

of the Side Seam Thermometer

by Bill Lockhart, Bill Lindsey. David Whitten and Carol Serr

© Bill Lockhart 2005

One of the longest running myths in theworld of bottle dating is that the side moldseam can be read like a thermometer todetermine the age of a bottle. The conceptis that the higher the side mold seam onthe bottle the later it was made – at least inthe era from the mid-19th century until thefirst few decades of the 20th century. Thisdating tool was apparently devised by GraceKendrick in her 1963 book The AntiqueBottle Collector. This book was apioneering effort and was reprinted manytimes into the 1970s. It is probably the mostcommon and widely quoted bottle book everwritten – by collectors and archaeologistsalike. Kendrick’s exploratory efforts werewell done – for the time period. She was atthe forefront of bottle researchers.However, we have learned a few things inthe past 22 years.

The concept of the side-seamthermometer was articulated by Kendrickin her chapter entitled “The Applied Lip”that contains a chart, “Age Gauge: MoldSeams of Bottles” (Kendrick1963:46).Kendrick explains in the text: “It is truethat the mold seams can be used like athermometer to determine the approximateage of a bottle. The closer to the top of thebottle the seams extend, the more recentwas the production of the bottle” (1936:45-47).

The chart accompanying this statementnotes that bottles made before 1860 have aside mold seam ending on the shoulder orlow on the neck; between 1860 and 1880,the seam ends just below the finish; between1880 and 1900, the seam ends within thefinish just below the top lip surface; andthose made after 1900 have mold seamsending right at the top surface of the finish,i.e., lip (Kendrick 1963).

Although there are examples of bottleshaving mold seams that fit these date rangesproperly, the issue of dating bottles is vastlymore complex than the simple reading ofside mold seams. If it were that simple,much of the succeeding literature andresearch would have been unnecessary. Forexample, the process that produces a tooled

finish frequently erases any trace of the sidemold seam an inch or more below the baseof the finish; whereas, the typical appliedfinish has the seam ending higher – rightat the base of the finish. Often the issue isthe skill of the individual craftsman. Ahighly-skilled bottle maker obliterated lessof the mold seam than one who was moresloppy in his work.

In addition, there are three other pointspertinent to side seam height. First, onmany 19th century bottles, the side seamsare a different height on each side.According to the thermometer, the bottlehalves would have been made duringdifferent years. Again, this is a result ofthe individual skill of the craftsman.Second, all glass techniques changed overa period of time. Not all mold makersproduced molds with higher seams duringthe same period. Even if the chart were agood indicator, it would have to have aperiod of overlap for each line height duringwhich the industry standards changed.Finally, most bottles made by handthroughout the mouth-blown bottle era(antiquity through the first quarter of the20th century) received varying amounts ofre-firing of the upper neck and/or finish.This reheating often erased traces of theside mold seams – further confounding the“thermometer” dating guide throughout theentire mouth-blown bottle era.

The final sequence in the chart, the sideseam extending to the top of the finish after1900 is extremely faulty. Many figuredflasks (like scroll flasks) were simplycracked off from the blowpipe at the pointwhere the top of the mold ended, with nore-firing of the lip. This leaves a relativelysharp, round lip surface to the bottle butalso often results in a bottle where the sidemold seams ends right at the top edge ofthe lip (but of course, does not go over thetop of the finish like a machine-madebottle). Although these flasks date to the“before 1860” period, the “thermometer”would date them into the 20th century!

In 1881, Phillip Arbogast invented asemi-automatic bottle machine, a device

that reversed the process of bottle makingby creating the “finish” first (Meigh1960:3). Forming the finish first createdside seams that extended to the top of thebottle. These early machines only workedon wide-mouth bottles and jars, but thetechnique was improved to make small-mouth bottles by late 1887 (Meigh1972:28). Even when Michael J. Owensinvented the Owens Automatic BottleMachine in 1903, that did not mean thatall or even most bottles began to have theseams extend to the top of the finish duringthat period. Many bottles continued to bemouth blown, meaning that the finish wascreated last, and side seams terminatedbelow the finish, until the mid-1920s (seeMiller & Sullivan for a good discussionabout the transition period).

The seam that extends into the finish, aprocess Kendrick dated 1880-1900, issomewhat unusual and is found in relativelyfew bottles. Lindsey (2005) describes thisas an “improved tooled” finish that is mostcommonly (but not exclusively) seen onbottles produced towards the end of themouth-blown bottle era, i.e., 1890s to1910s. While this can be dated reasonablywell to that time period, it was clearly nota defining technique for that or any otherperiod of time.

It is unfortunate that this fiction keepspopping up in the literature of bottle datingand identification ranging from Sellari’sbooks (Sellari and Sellari 1970:5 andothers) published shortly after Kendricksbook to as recent as Fike (1998:4) andHeetderks (2002:15). It is also frequentlynoted by sellers on eBay® when describingtheir offerings. The most recent repetition(with the 1880-1890 form slightly alteredfrom the original Kendrick chart) waspublished in the Summer 2005 issue ofBottles and Extras (Munsey 2005:31). Therest of Munsey’s article, by the way, isexcellent.

There is, of course, some truth in thethermometer concept. Over time, twoimprovements in bottle manufacturecontinued to advance. First, molds actuallydid improve, gradually creeping up the sideseams ever higher. While this idea, thebasis of the side-seam thermometerconcept, is correct, it is not clearlyarticulated enough in the actual practice of19th century bottle makers to be a usable,dating concept, especially not with clear-cut starting and stopping dates. Second,finishing techniques improved. As bothtools and the techniques of the bottle

Bottles and Extras Fall 2005 15

makers became more refined, less of thebottle necks were affected by the finishingprocess. Once again, however, this washighly dependent on individual gaffers(glass blowers) and the tools provided byspecific factories. It was not clear cut, andthere are literally dozens of examples inthe collection of only one member of thisresearch group that refute the side-seamthermometer fiction. Between the four ofus, we could probably provide literallyhundreds of examples that are exceptionsto the “thermometer” dating guide.

Examples of these are a bottle fromM. H. Webb, Druggist, of El Paso, Texas.Webb was only at the address on the bottle(220 San Antonio St.) from 1900 to 1903.According to the thermometer, this bottleshould have a side seam that extends to thetop of the finish. In reality [Figures 1 - 2],the side seam terminates less than halfwayup the neck. If the thermometer were to bebelieved, this bottle would date 1860-1880,at least 20 years too early.

A bottle from the Rio Grande Pharmacy[Figures 3 - 4], one of El Paso’s oldest drugstores, is embossed with the signature ofStafford Campbell, Ph.G., Prop. Campbellwas first listed as the proprietor in theEl Paso city directories in 1896, and he tookon a partner in 1901. Thus, the bottle wasmade during the 1896-1901 period andshould have a side seam extending to thetop of the finish (according to thethermometer). The actual side seamterminates slightly above the shoulder.According to the thermometer, that woulddate the bottle before 1860.

A third example comes from theEconomical Drug Co., open in El Paso from1915 to 1930 [Figures 5 - 6]. The style ofthis bottle, with graduations in ounces onthe left and cubic centimeters on the right,was first offered in the 1902 Whitall Tatumcatalog and was used until at least the1930s. The seam on this bottle extends tothe bottom of the finish on one side andless than halfway up on the other – clearlynot to the top of the finish. These examples,alone, clearly refute the accuracy of theside-seam thermometer concept.

Two final examples are found on softdrink bottles from the Magnolia Coca-ColaBottling Co., El Paso. The company wasfounded in late 1907 or early 1908 andobtained the Coca-Cola franchise in 1911(Lockhart 2001:83-98). Magnolia’s secondbottle style [Figures 7 - 8] was used fromabout 1909 to 1911. On all examples ofthe bottle, the side seams extend more than

Figure 1: M. H. Webb Drug Store Bottle (1900-1903)

Figure 2: Side Seam –Webb Bottle

Figure 3: Rio Grande Pharmacy Bottle (1896-1901)

Figure 4: Side Seam –Rio Grande Pharmacy Bottle

Figure 5: Economical Drug Co. Bottle (1915-1930)

Figure 6: Side Seam –Economical Drug Co. Bottle

Figure 7: MagnoliaBottling Co. Bottle

(1909-1911)

Figure 8: Side SeamMagnolia Bottling Co. Bottle

halfway up the neck but endwell below the finish – a formatthat fits the 1860-1880identification on the“thermometer” – at least 29years off. A straight-sidedCoke bottle [Figures 9 - 10] hasa side seam that extends intothe finish, an idea thaton Kendrick’s originalthermometer would have datedthe bottle between 1880 and1890. Because Magnolia didnot acquire the Coke franchise until 1911,this date range, too, is incorrect by at least21 years. The evidence speaks for itself.

We hope this helps clarify bottle datinga bit and will help persuade more people to

stop repeating this outdateddating technique. Kendrick’sideas were well thought out – forthe 1960s. However,researchers of the 21st centuryneed to update our body ofdating tools to reflect morerecent discoveries. For more

discussion on this aspect of bottle datingand identification, see Bill Lindsey’s“Bottle Body Characteristics & Mold Seamsand Bottle Bases” webpages.

Continued on Page 41.

Bottles and Extras Fall 2005 41

References:

Fike, Richard E.1998 “A Guide to Identificationand Dating of Historic GlassBottles.” Unpublishedmanuscript. Bureau of LandManagement., Colorado. Usedin the CDF ArchaeologicalTraining Program ReferenceManual.

Kendrick, Grace1963 The Antique BottleCollector. Old Time BottlePublishing Co., Salem, Oregon.

Lindsey, Bill2005 “Bottle BodyCharacteristics & Mold Seamsand Bottle Bases.” http://www.blm.gov/historic_bottles/body.htm and http://www.blm.gov/historic_bottles/bases.htm

Lockhart, Bill2001 “Magnolia Coca-ColaBottling Company.” Password46(2):83-98.

Meigh, Edward1960 The Development of theAutomatic Glass BottleMachine. Glass Manufacturers’Federation, London.

1972 The Story of the GlassBottle. C. E. Ramsden & Co.,Stoke-on-Trent, England.

Miller, George L. and CatherineSullivan

1984 “Machine-made GlassContainers and the End ofProduction for Mouth-BlownBottles.” HistoricalArchaeology 18(2):83-96.

Figure 9: El Paso – Straight-Sided Coke Bottle (1911-

1918)

Figure 10: Side Seam –Straight-Sided Coke Bottle

Munsey, Cecil2005 “‘The Smallest Bottle Ever Made on an Owens AutomaticGlassblowing Machine.’” Bottles and Extras 16(3):28-31.

Sellari, Carlo and Dot Sellari1970 “Eastern Bottles Price Guide.” Vol. 2. Area Printing Co.,Dunedin, Florida. [The thermometer was repeated in Volumes 3and 4, 1971 and 1972.]

Continued from Page 15.

due to two or three examples of this flask being made availablein the past year. The one to look for is the variant with Sam T.Bernard as proprietor – you’d certainly see me chasing it a lothigher than this!)

Please view my “Recent Find” at the beginning of the magazine.Although promised for this column, I do not want my readers toaccuse me of verbosity (nor brevity, it appears!), so I will breakoff at this point. I am especially interested in hearing from all ofyou about what you want to see covered in this column and whatyou have been finding, digging or might be interested incontributing.

Until the next issue……….Ralph

(For the reader who wants to learn about collecting Westernflasks I recommend the following texts by John L. Thomas:

Coffins, Picnics, ShoofliesWhiskey Bottles of the Old WestWhiskey Bottles and Liquor Containers From the State of

OregonWhiskey Bottles and Liquor Containers From the State of

Washington

The latter two texts both contain a very nice depiction of thevarious styles of “flat” and “miscellaneous” style flasks.)

Figure 13