Glass Insulator Embossings

 Embossings (Markings) 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!


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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 through that venue.

NOTE: For more information on the individual glass company/factory names mentioned below, please check out my webpage on GLASS INSULATOR MANUFACTURERS.

For a general discussion about glass insulators, including links to some 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
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
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

 

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Click here to go to the GLASS Manufacturers’ Marks pages.


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