Glass Insulator Embossings / Markings

  Markings (Embossings) seen on  Antique Glass Insulators (and their possible  glass  factory sources)

Below is a brief list of some embossed markings seen on insulators that stand for end user companies (or in some instances, a brand name or initials used by the glass company) which may not obviously indicate the factory that made the piece.  It would be difficult to extrapolate on subtle, minor embossing details that, in some cases, might distinguish similar-looking insulators as being products of a certain glasshouse.   As an advisory, I should mention that the information presented below is not guaranteed to be 100% accurate.   It’s to the best of my present knowledge, and I would appreciate any corrections or clarifications submitted, so please feel free to contact me if you can help out!

ADVERTISEMENT

I would also recommend consulting various reference books within the insulator collecting hobby, as well as other knowledgeable collectors, for more information on the subtle differences between the products of different glasshouses.  A very good source of info would be back issues of Crown Jewels of the Wire, the magazine of electrical insulator collecting which has been published since 1969.   Many informative articles have been published over the years in that magazine.

NOTE: For more information on the individual glass company/factory names mentioned below (and others not mentioned on this page) please check out my webpage on GLASS INSULATOR MANUFACTURERS.    On that page I list a number of glass insulator manufacturers that typically marked their company name (by default) on insulators, such as Armstrong, Whitall Tatum, Kerr, Brookfield, Hemingray, Dominion, California, McLaughlin, Lynchburg and others.

For a general discussion about glass insulators, including links to a number of other informative insulator-related websites, please check out my page  GENERAL OVERVIEW ON GLASS INSULATORS.     Thank you!!

PRIMARY EMBOSSING………..GLASS FACTORY SOURCE

• A. T. & T. …………………………………….Brookfield Glass Company
• Ampersand ( “&” sign, seen on CD 117)……………….. Brookfield
• AM TEL & TEL….Brookfield, Hemingray, Western Glass Mnfg.Co, Sterling
• B (on the side, normally below wire groove)………Brookfield B. & O. ………………………………………………….Brookfield, Hemingray
• B. G. M. CO……………………………………………………………Baltimore
• Birmingham………………………………………probably Lynchburg
  Brooke’s………………………….Uncertain New England-area glasshouse
• B.T.C…………………………………………………………..Diamond Glass Company?
• C.& P.CO…………………………………………………………..Brookfield
• C. D. & P. T. Co…………………………………………………..Brookfield
• C. D. & P. TEL. Co……………………………………………….Brookfield
• C.E.L.CO……………………………………………………………Unknown
• C.E.W…………………………..San Francisco or Pacific Glass Works
• C.N.R…………………………Unidentified Canadian glass company(s)
• C.P.R…………………………Unidentified Canadian glass company(s)
• Cable…………………………………..Brookfield, Hemingray, others
• City Fire Alarm…………………………………..Brookfield
• Columbia……………………………………..Hemingray, Brookfield
• Combination Safety……………………………………….Brookfield
• Diamond logo……………………………………..Diamond, Dominion Glass Company
• Diamond superimposed over oval and I…………Owens-Illinois
• Emerald…………………………………………………….. see “Prism”.
• E. L. CO. …………………………………..Brookfield or unidentified
• E.R. ………………………………………at least some are Brookfield
• E. R. W. ……………………………………………………………..Unknown
• Fall River………………………………………………………… Brookfield
• G. E. Co [General Electric Company] …………………………………………. Brookfield, Hemingray
• G.N.R………………………………………………………………… Diamond?
• G.N.W……………………………………………………………….. Diamond?
• G. T. P. TEL. CO………………………………………Canadian company
• H (on dome, beehive style insulator)………………………….Hemingray
• H. G. CO …………………………………………………………………..Hemingray
• H.G.W. (monogram)…………………probably Houston Glass Works
• H.I.CO (monogram) above  HAWLEY PA U.S.A……………….. Harloe Insulator Company, Hawley, Pennsylvania
• I (thin raised vertical line, on opposite sides of the skirt of beehive style insulator, with “H” on top)…………………………………Hemingray Glass Company
• Jumbo……………………………………………………………….Brookfield
• K. C. G.W. …………………………………………..King City Glass Works

ADVERTISEMENT

• Kimble………………………………………..Hemingray (Owens-Illinois)
• Knowles……………………………………………………………..Novelty
• KPP inside an oval ………………Kerr (Kerr Packaging Products Division)
• £ (British “Pound Sterling” Sign, looks like fancy cursive “L” with a horizontal dash through it) ………………………………………………Sterling Glass Co.
• L. G. T. & Co ……………………………………………………..Brookfield?
• Locke……………………………………………… Brookfield, Hemingray?
• Lowex………………………………………………………. Hemingray
• M.& E. Co…………………………………………………………Unknown
• McMicking………………………………….Uncertain Canadian company
• Montreal………………………………………………………….Diamond?
• Mulford & Biddle………………………………………………Unknown
• N.E.G.M.CO………………………………………..New England Glass Mnfg. Company
• N. W. & B. I. T. Co……………………….Unknown Canadian company
• N.Y.& E.R.R………………………………………………………..Unknown
• O.V.G.CO……………………………………………………….Ohio Valley Glass Company
• P in a diamond (CD 134)………………………………………………Unknown
• P in a diamond (CD 154)………….Canadian manufacture, probably Dominion
• P.R.R [Pennsylania Railroad]…………………………………………….Brookfield
• Paisley…………………………………………………………………Unknown
• Patent Dec.19 1871……………………………………………….Hemingray
• Patent Oct. 8 1907……………………………………………….Hemingray
• Patent Oct.8TH 1907 [NOTE “TH”]……………………..Brookfield
• Patent May 2 1893…………………………………………….Hemingray
• Pettingell Andrews……………………………………………Unknown
• Postal…………………….most are either Brookfield or California
• Pyrex………………………………………………………………..Corning
• “Prism” (raised embossed representation of a cut Emerald / Jewel / Gemstone)……………………………………………………… Novelty Glass Co.
• Santa Ana…………………………………………..California, Hemingray
• Seilers …………………………………………………………Hemingray?
• S.F [Unidentified Meaning] seen on CD 102 and CD 112………………………………………………………Unidentified manufacturer
• So. Mass. Tel. Co …………………………………………………Brookfield?
• “Star”…..Novelty, Sterling, Harloe, probably some made by Brookfield
• Sterling …………………………………………………………….Sterling
• Surge ………………………………………………………….. Hemingray
• T.H.E.CO …………………………………………… Brookfield, Hemingray
• T.C.R……………………………………Unidentified Canadian company
• Tillotson…………………………Brookfield; New Windsor Glass Works
• Twiggs……………………………………………………………….Unknown
• U.S.TEL.CO (CD 121)…………………………………………..Brookfield
• Westinghouse …………………………………………………..Unknown
• W. E. MFG. CO…………………………………….Brookfield, Hemingray
• W.F.G.CO…………………………………….Western Flint Glass Company
• W.G.M.CO………………………………..Western Glass Mnfg. Company
• W.U [Western Union]……………………………. Brookfield, Hemingray

Please click here to go to my website HOME PAGE.

Please click here to go to Page One of the alphabetical listing of marks seen on glass bottles, jars, insulators and tableware:   Glass Bottle Marks, Page One