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By Frank Swies

A collection of known facts and common lore surrounding the North American, pin type, threaded glass insulator embossed with a five-pointed star.

Discussing star-embossed, glass insulators is very much like discussing the Loch Ness Monster; there are hundreds of beliefs and stories but little definitive information. Sadly, records are scarce to the point of virtual non-existence. Why they were made, when, where and by whom remains open to investigation. This is an attempt to present existing information, both factual and anecdotal.


The number of styles that bear the STAR embossing has become known from actual sightings. Styles are identified with the Consolidated Design (CD) numbering system devised by N. R. Woodward (1). Star insulators are know to exist in the following CDs:

102 104 106 112 113 133 134 145 160
161 162 162.1 162.3 164 185 200 260  


Embossing on glass insulators served two principle purposes; the first use was to identify the manufacturers (i.e. BROOKFIELD, HEMINGRAY), the second was to identify the customer/user for which the insulator was made (i.e. T-H.E. CO., CITY FIRE ALARM, POSTAL TELEGRAPH CO., A.T.&T.). Which purpose did the star embossing serve?

The Mansfield-Nowlton Glass Works of Lockport, New York manufactured bottles, fruit jars and other utility glass items which bore their logo, a five pointed star. There is known to have been an embossed star logo used by the Newark Star Glassworks of Ohio. The ACME Glass Company also made use of the five pointed star mark, there was also a STAR Glass Company in New Albany, Indiana from 1860 to 1900. No evidence has emerged to show that these star logo companies ever manufactured glass insulators.


The Sprague Electric Railway and Motor Company of New York had unexpected growth during the years 1888 and 1889. They contracted to connect a hydroelectric generating station to fourteen Sprague motors along an eighteen mile circuit. This circuit was to provide power to the new gold mining efforts and demand for electric street railway service. Quality problems cause extensive rewiring of the Sprague motors. This, plus internal conditions, placed a great demand on financial resources and threatened the economic survival of the company (4).

During this same time period several Edison operated companies merged into a single entity known as the Edison General Electric Company. This company provided for the needs for municipal electric lighting and could only meet these needs by expanding it’s facilities.

Sprague needed financial health and Edison was poised to enter the market of electrical power. Sprague was soon absorbed by Edison General Electric and a new company , The General Electric Company (G.E.), resulted. Its goal was to supply electric power on an unprecedented scale.

The Thomson-Houston Company was engaged by G.E. to provide the necessary transmission equipment. Research by Joe Maurath, Jr.(5) discloses that the Thomson-Houston never produced glass insulators. Instead, Brookfield and Hemingray were contracted to produce the desired glass insulators. Why was this important? Examination of a 1904 General Electric Company catalogue (see attachment 1) reveals that the following glass insulators were offered:

Cat. No. 9322   Pony Glass Insulator
Cat. No. 9310   Deep Groove, double petticoat insulator
Cat. No. 9311   Extra Deep Groove, double petticoat insulator
Cat. No. 9312   Pony, Deep Groove, double petticoat insulator

These items deserve particular attention because they are all marked with an embossed five pointed star. Today we refer to these same insulators as CD 112, CD 161, CD 162, and CD 160 Respectively. N. R. Woodward relates that the General Electric had insulators made for them that were embossed with a raised five-pointed star. It seems safe to assume that the five pointed star embossing was intended as a users mark for General Electric items.

WHO MADE ‘EM? . . . WHERE? . . . WHEN? . . .

Prevailing belief is that there were several glass producing companies involved in manufacturing star-embossed insulators: Hemingray, Brookfield, Sterling, Novelty and Harloe.

William L. Brookfield, in an interview with Carol McDougald (6), stated that he believed that insulators with embossed stars were made at the Brookfield Glass Company plant in Old Bridge, New Jersey. This is possible since G.E. came into existence in 1903 and the plant at Old Bridge was already producing insulators for the Thompson-Houston Electric Company (T-H E. CO.). These molds were ultimately retooled to G. E. CO. and subsequently, a Star after Thomson-Houston became part of G.E.

In 1902, the old Elmer Glass Works of Elmer, New Jersey, leased spaces to the Sterling Glass Company. The following year, the company was sold to the Harloe Insulator Company of Hawley, Pennsylvania. This facility, known as the “Lower” works, produced glass insulators sporadically due to fuel shortages. The insulators produced were of the CD 102, CD 112, CD 160 and CD 164 variety. Things did not go too well and in October, 1903 the Harloe company vacated the plant and moved production to Hawley, Pennsylvania.

In 1903, the property of the Gilchrist Jar Company, located in Elmer, New Jersey, was sold at auction to the Novelty Glass Manufacturing Company. The plant, known as the “Upper” works, began producing glass insulators as it’s main product. A patent infringement suit, brought by the Brookfield company, caused the plant to close in 1907

In 1980, excavation at the site of these works by Ray Klingensmith, revealed remnants of star insulators and other variations. It is evident that Sterling , Harloe and Novelty produced star-embossed glass insulators for G.E. for a short time at these Elmer works.

Prior 1912, needs for insulators, west of the Rockies , had been provided for by the Brookfield and Hemingray companies (7). Hemingray was already producing CD 134 (aqua-green) insulators for the T-H. E. company when it became part of G.E. It is quite possible that the molds were retooled to a star at a later date .

COLOR CLUES . . . . .

Color and quality are invaluable aids in determining origins of star insulators. Common colors range anywhere from light blues to dark greens. These colors are determined by the sand source primarily, however, the use of cullet and additives will alter resulting colors. The main drawback to identifying by colors lies in the fact that color determination is very subjective. (How many collectors feel confident in discerning between teal green and dark green aqua?) Add variable light sources and the possibility of color impairment of the viewing person and color determination can offer a challenge.

When the Brookfield plant was built at Old Bridge the colors produced were different from those coming from Bushwick in Brooklyn. Old Bridge used a good deal of cullet with their New Jersey sand and a pronounced green color resulted (i.e. Dark aqua, dark green, olive green).

Novelty Glass Company operated the “upper” works at Elmer. New Jersey sand was used and the resulting glass was green.

Sterling operated at the old Elmer “lower” works. One noticeable quality present in Sterling insulators is the purity of color. Quality control is evident in the clear light blue aqua color glass that was produced.

Harloe had a plant in Hawley, Pa. and produced insulators from 1902 through 1907. The sand quality and the use of cullet and additives produced a crude aqua to blue aqua glass that is sometimes referred to as snowy, milky or “gunky”. Do not confuse Harloe with the Hawley glass company of an earlier time (ca. 1872 - 1885).

Prior to 1889, Hemingray operated a plant and offices in Covington, Kentucky. The glass produced ranged from blue to green in a very unpredictable color. 1890 – 1930 saw the construction and continuous operation of a second plant in Muncie, Indiana. A more uniform blue-green color glass was produced. Color alone is not a very reliable identifier. A 1896 Hemingray Letter-head claims “Flint, Green, Amber and Opal Glass Manufacturers”.


One of the oddities of STAR insulators that is mentioned from time to time is the wedge-shaped drip point (see attachment 3, Figure 1). From appearance it could be assumed that the wedge is formed by bridging two adjacent drip points. There are two styles of STAR insulators that exhibit this feature: The CD 102 pony and the CD 162.3 signal. The purpose of this design is unknown as is the manufacturer; however, they both exhibit swirl start threading which is considered by many as a Brookfield characteristic.

Another oddity that is occasionally observed is the "Elmer Ring." This expression refers to a half inch circular impression made in the top of the pin hole. The prevailing belief is that this impression is made by a unique mandrill used by the Novelty Glass Co. which was reused by other, subsequent operators of the works in Elmer, New, Jersey.

All star-embossed insulators were produced by the use of three-piece molds (no MLOD). An exception exists in the case of the STAR mine insulator (CD 185) which used a two-piece mold. Variants are sometimes found believed to be caused by the exchanging of molds by the Elmer companies.

An attempt to correlate STAR attitudes, size and colors with manufacturers proved inconclusive.

There are no recorded instances of any clear glass STAR insulators being found.


Presently, there are 17 styles of star-embossed glass insulators that are known. When the variety of embossing styles are considered, the number jumps to 38. Add to this the possibility of multiple manufacturers, numerous mold styles and color variations and the task facing the prospective STAR collector becomes challenging. The following is a brief introduction to the family.

CD 102

The STAR pony “herd” is possibly the largest group of STAR insulators. McDougald’s vol. 2 lists the known embossings as follows:

Index        Description
010 Dome Number, STAR on front skirt, smooth base
020 Dome Number, STAR on front skirt, sharp drip points
030 Dome Number, STAR on front skirt superimposed over a partially blotted out S.F., smooth base
040 Dome Number, STAR on front skirt superimposed over a partially blotted out S.F., sharp drip points
050 STAR on front skirt, smooth base
060 STAR on front skirt, sharp drip points
070 STAR on front skirt, small vertical bar on rear skirt, smooth base
080 STAR on front skirt, STAR on rear skirt, smooth base
090 STAR on front skirt, wedge-shaped drip points
100 STAR on front skirt, very small STAR on rear skirt, smooth base
110 STAR on front skirt superimposed over a partially blotted out S.F., smooth base
120 STAR on front skirt superimposed over a partially blotted out S.F., sharp drip points

One long time collector (Brent Berger), has developed a method of classifying STAR ponies by mold sets (see attachment 2). The belief was that the embossing index system does not reflect the subtle nuances of the various manufacturers mold variations. Much can be said favoring his system (but a sharp eye is required). This method of CD 102 STAR mold set designations provides a visual identification.

Tall Skirts
This mold set is very common with many subvarients. At first glance, most of the skirts seem alike; however, dome profiles vary from short, sharp edged to tall and rounder.
Fat Heads
Characterized by slightly larger domes. Skinny Skirt and Stout Skirt variants exist. The Skinny Skirt tends to be slightly taller than the Stout Skirt version. Some of the Skinny Skirts have concave sides.
Shrunken Heads
This set constitutes a unique union of a Stout Fat Head skirt with the dome of another, undersized set.
Shotgun Skirts
These very common, smaller insulators have STAR embossing on the front and rear skirts. The sides are almost parallel lending to a “gun barrel” appearance.
S. F. Style
These are created from reworked S. F. Insulators. The second period is visible. There are smooth base and sharp drip point versions existing.
Taller, oversized, round domes styles embossed front and rear with a STAR. There exists a less round dome version with a sharper upper wire ridge.

There are several features of STAR ponies that seem unique and bear repeating. Some of the CD 102 STAR ponies (Index 010, 020, 030 and 040) are numbered on the dome; numbers 1 through 3 are common. Dome numbering (mold numbers) is not unique to STARs however, since it was a common practice of Brookfield to use dome numbers and letters; Hemingray made use of dome letters . The facts that several STAR ponies carry dome numbers and are found mostly in darker green colors prompts the belief that Brookfield was involved in the production of these STAR ponies.

Several STAR CD 102 ponies have sharp pointed drip points. Hemingray patented the drip point feature in 1893 and it was not until expiration of this patent that other manufacturers used drip points. In the early years, following 1893, drip points were considered a unique Hemingray feature. There is, however, a strong belief that the sharp drip point STARs were produced by Brookfield. This belief has not been substantiated.

In descriptions, the feature of an embossed STAR superimposed over a blotted out S.F. is very often used to refer to certain STAR CD 102s. It appears that in the retooling of S.F. molds, the second period was overlooked and remains as an adjunct to the STAR embossing. Whoever made the S.F. insulators evidently was involved in STAR production (see attachment 3, figure 2).

There exists an unusual mark on the STAR ponies that is seldom, if ever, observed in other insulators. This feature is sometimes called a vertical bar. The bar is much smaller than is normally encountered with a conventional vertical bar (see attachment 3, figure 3). The 3/16 inch vertical bar (Index 070) resembles a “seepage” from the edge of an elliptical blot-out. What was blotted out is open to conjecture but the dimension (1/2 inch) would allow for the removal of a “B” embossing (normally inch) or perhaps a smaller star. Several of these pieces have been seen so this is not a one-time anomaly.

Some interesting insights can be gained by comparisons. Compare the following CD 102s:

STAR[080] (Shotgun) Hawley [050]
STAR[040] (S.F. Style) S. F. [020]
STAR[050] (Fat Head, Skinny Skirt) Sterling [020]
STAR[050] (Fat Head, Skinny Skirt) Brookfield [020]

The similarities are striking and could possibly lead to the assumption of manufacturer that may, or may not be valid.

CD 104

This insulator was designed for subscriber and open wire telephone use. N. R. Woodward and M. Milholand refer to this style as a PONY, Tibbits called it a BEEHIVE (8) and Brookfield called it a NATIONAL PONY. The known manufacturers of this style (Brookfield, National Insulator Co. and Standard Glass) retained a great degree of similarity in design. The dimensional differences are shown in attachment 4.

The CD 104 STAR occurs in one embossing style [010] which features a single star, skirt embossing. There are, however, variations in the size of the star indicating variety of molds used. Colors encountered are predominantly light blue and light aqua with occasional green and green aqua being found.

There occasionally emerges discussion concerning a “wide base variant” of this piece. The only “wide base variant” CD 104 that has been recorded is that of the New England Tel & Tel CD 104 (9). There are no records indicating that the CD 104 was made at the Elmer, N.J. sites even though the “Elmer Ring” is sometimes observed.

CD 106

CD 106, nicknamed PONY, was designed to serve primarily rural telephone systems. The style was widely copied and produced by many of the major insulator manufacturers. Curiously absent from the wide production is the Brookfield product. None have been observed. Dimensions are relatively consistent with the sketch shown in attachment 4.

The CD 106 STAR has been widely used and has been found in virtually every quarter of the country. The one notable exception seems to be the Southwest. There seems to be no geographic focus of usage.

A sample of fourteen CD 106 STARs produced some very interesting results. All of the items sampled were embossed with a single star (index 010). In every case, the star measured 1/2" and consistently pointed downward. It is easy to believe that the single mold pattern (manufacturer) is the reason for this consistency. This may well prove erroneous because of the wide range of glass colors found. Common colors range from light blue through aqua to a darker green. All had smooth bases while other versions of CD 106 had drip points. The source of the CD 106 STAR remains open to conjecture.

CD 112

The CD 112 double groove insulator, nicknamed double groove pony, was designed for residence drop line / exchange line interface. This style insulator was developed and produced for nearly 20 years by Brookfield. Star embossed fragments of this style have been unearthed at the lower works site of the Sterling Glass Works (after acquisition by Harloe in ’03). Colors are generally aqua with occasional green shading from light green to dark olive.

Current literature lists two embossing indices for the CD 112 STAR; [010] single star and [020] double star embossing. In reality, five mold variations have been encountered. They are shown in attachment 4 as follows:

[010]       Flat Side, Sharp Corner, one star
[010] Flat Side Tall, Sharp Corner, one star
[010] Flat Side, Rounded Corner, one star
[010] Barrel, Rounded Center, one star
[020]  Flat Side Tall, Sharp Corner, two stars

The [010] Flat Side Tall is seldom found and can be considered a rarity. Physically, the dimensions are identical to the [020] Flat Side Tall. It could be helpful to remember that “rounded edge” molds are a familiar Brookfield trait, sharp edges are found in Hemingray.

CD 113

At least four glass companies are known to have produced the CD 113 double groove pony. This insulator, designed to serve rural exchange telephone lines, was manufactured by Armstrong, Hemingray, Westinghouse, Whitall Tatum and possibly others. Exactly who it was that produced the star-embossed units is yet to be documented.

Colors usually found range from light blue, through aqua to an olive green.

The most often found CD 113 appears to be the Hemingray #12. It is a temptation to attribute STAR 113 production to Hemingray . This could prove to be a false assumption because the STAR 113 is a smooth-based unit and Hemingray produced units with drip points. In addition, the Hemingray unit has a decidedly different threaded pin hole with an extra thickness of material to reinforce the lower wire groove since the threading begins above the wire groove. The STAR 113 has threading that extends below the wire groove and offers sufficient thickness to support a lower wire groove (see attachment 5, figure 1).

A theory periodically emerges that suggests that the CD 113 STAR was made from reworked CD 106 STAR molds. From outward appearance it would seem possible but in practical terms it is not likely. The bottom of the pin hole/inside skirt of the two insulators are markedly different (see attachment 5, figures 1 & 2). The skirt wall of the CD 106 seems to be too thin to safely support an added wire grove. Yet, occasionally one hears of a collector finding a CD 113 that has the area below the lower wire groove broken off. No support for the for the “rework” theory has been uncovered.

CD 133

This smaller version STAR signal (see attachment 5, figure 3) was intended for use with open-wire telegraph, telephone lines and other low voltage applications. The lack of an inner skirt prohibited use with high voltage circuits due to the short distance from line to ground (mounting pin).

The CD 133 STAR is sometimes referred to as a “bullet” due to its narrow dome. The colors range from light blue through aqua to various shades of dark green suggesting the possibility of Novelty Glass or early Brookfield origins. Most of the CD 133 STAR signals have the “elmer ring”.

One existing belief is that the CD 133 evolved from early CD 726 - 728.8 straight sided threadless signal insulators thus accounting for its smaller size. This evolution took place at a time when glass producers were retooling from threadless to threaded insulators in an effort to meet increasing demands (c. 1865 – 1875), but, once again, this is speculation.

CD 134

The CD 134 insulator, known as a deep groove signal, was used to carry Thompson-Houston circuits in late 1890s. The Hemingray made insulators bore the T-H E. Co. embossing and are found in aqua to light green colors. Brookfield is also believed to have produced the CD 134 for Thompson-Houston. When the change to General Electric occurred, the molds were retooled to the G. E. Co. embossing. Production continued until the closing of the plant in 1922. These Brookfield pieces are found in darker colors (dark green, dark aqua and olive green).

The CD 134 STAR has characteristics of both Brookfield and Hemingray. The two pieces are similar in dimension (see attachment 5, figure 4) and can be identified only by color and quality. The “elmer ring” is not present. No inner skirt was used.

CD 145

The CD 145 “Beehive” was intended to replace the much older “Compromise” insulator. Samuel Oakman’s 1884 patent (#14,674) design was adopted for open-wire telegraph use. Several supply houses manufactured this design. McDougald’s price guide mentions three commonly seen embossing styles:

[010]      “Standard”, single star, smooth base
[020] “Pointed Dome”, single star, smooth base
[030] “Postal Style” or “Tall Dome”, single star, smooth base

Variations of these styles have been collected but they are still considered in the [010] index (see attachment 6). All of these five styles have smooth bases and short inner skirts not extending as far as the outer skirt. Colors range from light blues through aqua to variations of dark green. Identification of manufacturer is complicated by the color variations and dimensional differences. These variations suggest that the CD 145 STAR was made by several sources. The Standard, Pointed Dome and Tall Dome styles are believed to be products of the Elmer, NJ glass companies (Sterling, Novelty and Harloe). The variants suggest that Brookfield and Hemingray were involved in the production of CD 145 STAR insulators using modified mold embossings. The Brookfield connection with Novelty Glass is questionable because, at that time, Brookfield was suing Novelty over a patent infringement (10).

Distribution of the STAR CD 145 seems diverse; examples have been found in Ontario, Canada as well as various parts of the U.S.

CD 160

The CD 160 STAR insulator (see attachment 7) were originally intended for rural telephone system use. It is a smaller signal type with a smooth base, a single star and inner skirt which does not extend as far down as the base. It is not to be confused with a CD 133 which does NOT have an inner skirt.

The color distribution ranges from light aqua through yellow green to light yellow aqua. The size and attitude of the star embossing together with the color glass provides an interesting subject of speculation.

Small stars (3/8"), pointing downward are found on the darker aqua insulators. These same insulators are made with wider wire ridges suggesting Brookfield origins (no Elmer ring).

A slightly larger star (7/16"), pointing upward is found in aqua and light aqua insulators with an “Elmer ring.” These insulators have a more conventional tapered wire groove suggesting Harloe (lower works) origin prior to the relocation to Pennsylvania.

A third type of star is found on the light blue and light green insulators which contain impurities and bubbles. The star is large (1/2 in.), pointing upward. The clear colors suggest Novelty glass.. An “Elmer ring” is found.

CD 161

An early (ca. 1904) General Electric supplies catalog includes a picture of a “Deep Groove, glass, petticoat” insulator. A cut-away picture reveals an inner skirt that does not reach to the base level.

N. R. Woodward shows only three companies involved with the CD 161; California Glass, Brookfield and STAR (11).

California glass tended towards a complex darker color while Brookfield glass has a characteristic darker green color. This color difference supports the belief that the Brookfield company produced the CD 161 STAR. Most of the STAR 161s are a green to darker green color. In addition, the California Glass Insulator Company was less likely to have had a connection with STAR manufacture because of its late start-up date (ca.1912). Harloe is believed to have made STAR CD 161 units after taking over the Sterling operation.

The CD 161 STAR is found with both a smooth base and sharp drip points (see attachment 7). Embossing includes a single star. Colors range from aqua through green to dark green. Embossing is of uniform configuration (7/16 inch star pointed downward).

Occasionally the CD 161 STAR and the CD 162 STAR are confused. Close examination discloses that the CD 161 STAR crown is relatively flat and wide (“broad shouldered”) and the skirt almost vertical (85 degree slope). The CD 162 STAR crown has a narrow, rounded inclined crown (“narrow shouldered”). The skirt of the 162 is at a greater angle (approx. 82 degrees); the base is also wider.

CD 162

The CD 162, referred to as a “deep groove, double petticoat”, was made for use with insulated drop lines and 6 to 8 gauge secondaries. The STAR CD 162 was manufactured by several of the prominent glass companies in the early 1900s ; Novelty Glass, Sterling and Harloe after it’s move to Hawley, Pa. Excavations at the Elmer “lower works” in 1980 produced fragments of Harloe type STAR CD 162 (12).

Current literature provides three embossing indices for the CD 162 STAR:

[010]       Smooth Base, Single Star
[020] Sharp Drip point, Single Star
[030] Smooth Base, Two Star

Colors range from aqua to dark olive green for the [010] index and aqua to olive green for the [030]. No example of the [020] has been found.

Three mold styles are found (see attachment 7):

Wide Dome
A common smooth base piece, ” wire groove, larger (1/2”) star pointed downward, an elmer ring is frequently present.
Narrow Dome
Frequently found smooth base, ” wide groove, one or two 7/16” star pointed downward. The elmer ring is present.
Wide Groove
A seldom seen variation, smooth base, 3/4” wire groove, single 7/16” star pointed downward. The elmer ring is usually present.

The narrow dome, wide groove style has been the subject of much discussion within the insulator community (ICON - Insulator Collectors On the Net). Some believe that it resembles a wide groove CD 161.2 because of its wide, flat wire ridge. Woodward concurs, however, no such listing is found in the McDougald literature. The assignment of embossing index numbers is made by McDougald. The dilemma was referred to Woodward and McDougald in 2001. Resolution is pending. Until such time as the literature is changed it will be customary to consider the narrow dome, wide groove style as a CD 162 STAR [010] variant.

CD 162.1

The Brookfield Glass Company catalogue of 1912 describes the style number 36 as a deep groove double petticoat insulator which features a slightly larger wire groove (5/8”) than is usually found. The dimensions shown are identical to those of the CD 162.1 STAR signal (see attachment 8). This similarity would lend credence to the circulating story that this STAR insulator is not an Elmer product but rather a Brookfield insulator from the later years.

Tibbitts (13) attributes the design to Samuel Oakman’s patent #288,360 (Nov. 13, 1883), however, this patent also covers the earlier Brookfield CD 162. Why the heavier crown and more squared top was designed is not known.

Colors of the Brookfield No 36 range from aqua through green aqua to dark aqua. This would seem to include the green aqua frequently found in CD 162.1 STARs.

CD 162.3

A small wire groove signal insulator, said to be the predecessor of the CD 162, was intended for use with bare wire or insulated wire smaller than 10 gauge. Only two sources of this piece have been reported: Brookfield and STAR. The STAR identity is ambiguous at best. The ice blue, steel blue, gray, and light aqua colors encountered would suggest Harloe origins and the dark greens sometimes found are a Brookfield type of glass.

McDougald assigns two embossing index numbers to the CD 162.3 STAR:

[010]       Single downward pointing star, smooth base (see attachment 8)
[020] Two downward pointing stars, wedge shaped drip points

In reality, the [010] index is not as descriptive as it should be. Close examination of these pieces discloses at least six mold variations. The variations, although relatively minor, represent items to be considered. The mold variations are as follows:

CD 164

A double petticoat insulator referred to as an “Extra deep groove DP signal” was made by several glass companies for use with ” cable, electric street lighting and street railways. Brookfield, Hemingray, Sterling, Harloe and others marketed this insulator under a variety of model numbers. The 1904 GE equipment catalogue shows an extra deep groove insulator as #9311. Brookfield made them as #487.

Harloe took over the Sterling operation (lower works) in 1903 then moved the operation to Hawley, Pa. where it manufactured insulators until 1907 when it assigned all patents to Brookfield. When Sterling moved to Hawley, the Harloe Insulator Company was already making CD 164s embossed HICO. The retooling of the molds to STAR would have been a simple task.

McDougald (14) shows a CD 164 STAR and assignees three embossing indices to it:

[010]        Single star, smooth base
[020] Single star, sharp drip points
[030]  Single star, smooth base, blotted circle on rear skirt

The colors range from aqua through green to dark olive green. The [020] model is reported as being only in aqua. No CD 164 STAR [030] has been found. There is, however, a Brookfield CD 164 with off-center B embossing and a circular blot out in mid rear skirt.

Close examination of a group of CD 164 STAR insulators reveals three mold varieties:

This single star shape with darker green colors and nearly vertical skirts suggests Brookfield origin. The dimensions and characteristic rounded dome compare to the Brookfield #38. The slight rounding of the lower wire groove edge is consistent with the “soft edge” trait found in many Brookfield insulators. An elmer ring is sometimes present.
Features a slightly flatter dome ridge. Found in both with and without drip point models in darker aqua hues. The soft edge and color suggest Brookfield glass. This same oval dome is seen on the Sterling and Harloe CD 164 insulators suggesting Sterling manufacture either at the lower elmer works (1902-03) when Sterling operated the facility or later in Hawley, Pa.(1903-1907) when Sterling was taken over by Harloe. An elmer ring is sometimes present.
A round dome, smooth base variation with colors predominantly blue aqua. The identifying characteristic of this variant is a convex downward curve of the lower wire groove edge where it joins the base ( similar to the H I Co pieces). There is a noticeable widening of the base. No elmer ring is found.

These three mold variations are illustrated in attachment 9.

CD 185

This mold style was created to provide insulation for low voltage applications found in mines. At the start of the twentieth century there was a growing market for such an insulator for use in the ever-growing numbers of gold, silver, copper, coal, etc. mines.

Only four suppliers of note are known to have provided CD 185 insulators: Brookfield, Hemingray, Jeffery and Knowles. Knowles is known to have sold products from other factories, including Brookfield (16). Hemingray made insulators for the Jeffery Mining Company (17). This design was patented (#526,498) by David Osyer and assigned to Hemingray.

Current price guides indicate only one embossing index number for CD 185 STAR mine Insulator; [010]. In reality, there are slight variations in dimensions (see attachment 9). The insulator has a threaded hole, smooth base made from a two-part mold. CD 185 STAR mine insulators have not been found with drip points. Colors range from aqua to shades of green which suggest Hemingray origins. The insulators are much sought after by collectors due to their rarity and usually command a high premium.

CD 200

Telephone system requirements usually included “Transposition Insulators” such as CD 200. The concept of two wire grooves and two storm shields with one skirt between the grooves was first introduced by N. Rousseau in 1883 (Patent #289,449). His design underwent several modifications before the present CD 200 Transposition resulted.

N. R. Woodward identifies Brookfield as being involved with the CD 200. There may well be other sources. Letters of patent (#520,367) were issued to Fred Locke in 1894 covering a “Transposition Insulator.” Because of an earlier contract with Brookfield to make his glass insulators, it could well be assumed that Brookfield made his transposition as No. 52. A comparison of the Brookfield 52 and the CD 200 STAR shows them to be virtually identical thus Brookfield appears to be the likely manufacturer (see attachment 9).

Colors range from blue aqua through light green to yellow green. The glass appears relatively free of impurities and tends toward greenish colors as found in Old Bridge Brookfield products.

Embossing index number [010] is used to describe this one-piece, smooth base transposition. A small (3/8”) star, pointing downward, is found on the skirt. There is no elmer ring in evidence.

CD 260

The CD 260 Cable insulator traces its origin to the efforts of Samuel Oakman (Patent 430,296 dated June 17, 1890). This unique insulator, called the “Roman Helmet”, (not to be confused with “Mickey Mouse” or “Viking Helmet) was designed to insulate heavy wires and to serve as a temporary holder for heavy wire or a permanent wire holder used to make turns.

Two embossing index numbers are used to designate the STAR CD 260 mold varieties:

[010]     Large (5/8”) downward pointing star, smooth base
[020] Large (5/8”) downward pointing star on front skirt “PATENTED. JUNE. 17. 1890” on rear skirt, smooth base

The only recognized makers/users of this insulator style are the California Glass Insulator Company and the Harloe Insulator Company. It is suspected that the Harloe works produced CD 260 STAR insulators for a time using reworked Sterling molds. California glass was a darker, more complex hue (purples, smoky rose, dark plum, blue green, etc.) Two mold styles of the California CD 260 were produced:” wide” groove and “pinched” groove. California Glass was not known to or suspected of producing STAR embossed CD 260 insulators. The blue aqua through light green to darker green glass colors of the CD 260 STARs appear consistent with the Harloe glass of Hawley, Pa. The darker colors probably resulted after the 1907 assignment of patents to Brookfield. (see attachment 10) This style of STAR insulator is considered rare and often commands a high premium.

TIE DOWN . . . . .

Some collectors gather glass insulators because of their variety, form and symmetry, others appreciate the color variations of sunlight on the insulators in their windows or out on the crossarms. The STAR collector, however, gathers a part of history. These STAR insulators were a basic part of the communications and power industries’ entry into the 20th century.


(1) N. R. Woodward, 1988 Report, Glass Insulator In America

(2) McDougald, 1990, History and Guide To North American Glass Pin Type Insulators ,vol. 1

(3) Milholland, 1972, Most About Glass Insulators

(4) John W. Hammond, 1941, Men and Volts – The Story of General Electric

(5) J. Maurath, 1990, New England Manufacturers, History and Guide to North American Pin Type Insulators

(6) C. McDougald, 1999, A Conversation with William L. Brookfield, Crown Jewels of the Wire, December, 1999

(7) McDougald, 1990, History and Guide to North American Glass Pin Type Insulators, California Glass Insulator Company chapter, pg. 90

(8) John C. Tibbitts, A Guide for Insulator Collectors, vol.2, 1968, item 2-96

(9) Marion C. Milholland, Most About Glass Insulators, 1972, pg. 28

(10) The Elmer Times, December 11, 1903 edition

(11) N. R. Woodward. 1988 Report, The Glass Insulator In America, pg.58

(12) R. Klingensmith, McDougald vol. 1, Glassmaking in Elmer at the turn of the century

(13) John C. Tibbetts, A Guide For Insulator Collectors, Vol. 1, 1967, item 47

(14) McDougald, 1990, History and Guide to North American Glass Pin Type Insulators ,vol 2

(15) J. C. Tibbetts, A Guide For Insulator Collectors, Vol. 1, pgs. 28, 29

(16) N. R. Woodward, 1988 Report, The Glass Insulator In America, pg. 43

(17) McDougald, 1972, History and Guide to North American Glass Pin Type Insulators, Vol. 1, pg. 147

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Last updated Saturday, November 27, 2004