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The Dominion Glass Company

by Steve GoodellView Icon Profile

This article is specifically about insulator production at the Dominion Glass Company, but first, a bit about the company itself.

Recently acquired documentation has proven that the Foster Brothers of St. John, Quebec and the Yuile Brothers of Montreal, Quebec were associated in business. Therefore, the early Foster Glass Works is authenticated as being the parent company of the Dominion Glass Company Ltd.

Documentation proves that the Foster Brothers -- George, Henry and Charles -- arrived in St. John from the United States some time prior to 1857, and that the Fosters had blown glass in Canada and the United States. Their factory produced containers of many sizes and forms, as well as telegraph insulators. They had two hand-operated insulator presses.

The Foster Brothers glass factory was bought by the Yuile Brothers in 1878 and renamed the Excelsior Glass Company. In 1880 they moved the operation to Montreal and remained there until 1883. In 1883, they transferred to another location in Montreal and changed the name again to the North American Glass Company, incorporated in 1883. The firm operated under that name until 1891 when it became the Diamond Glass Company. Operations were carried on under that name until 1902. In that year, the name was changed to the Diamond Flint Glass Company Ltd. The Diamond Flint Glass Company Ltd. acquired control of the all-important Burlington Glass Works, the Hamilton Glass Works, the Nova Scotia Glass Company of Trenton, Nova Scotia, the Lamont Glass Company, and, through its successor the Diamond Flint Glass Company, additional glass factories in Quebec and Ontario.

The Diamond Glass Company, Montreal, was the dominant co-operative group of glass manufacturers in Canada from the period 1890-1902. The incorporation which resulted in the new name, Dominion Glass Company Ltd., in 1913 included all plants which were directed by the Diamond Flint Glass Company.

In addition to insulators, the Dominion Glass Company manufactured large quantities of bottles, tumblers, lamp chimneys and other assorted glassware.

Design of Insulators

Five designs of insulators were manufactured, as follows:

No. 9 Telephone CD 108
No. 10 Telephone CD 115
No. 16 Telephone CD 122
No. 42 Telegraph CD 154, 155
No. 614 Hydro CD 164

CD 108, No. 9 was first produced on May 3rd, 1927, and was still being produced on August 25, 1959. This insulator is found with round drip points, sharp drip points, and smooth base variants. The colour range includes clear, straw, peach, light green and Delft blue. The price range of this insulator is $1-$50.

CD 115, No. 10 was first produced on April 10, 1927, and production was discontinued on April 18, 1939. This insulator comes with round drip points. Colours range from clear, straw and dark straw to light green. The value of this piece is in the range from $1-$10.

CD 122, No. 16 was first produced on February 6, 1927, and continued production until August 1959. This insulator is still used in rural Ontario and throughout Canada. This piece is found with round and sharp drip points, as well as smooth base variants. The colours are clear, light green, straw and light peach. The value of this piece is $1-$2 due to its availability.

CD 154 and CD 155, No. 42 was first produced on February 6, 1927, and was still being produced in August 1959. Earlier No. 42 insulators were of CD 154 design, and then at an unrecorded date changed to the CD 155 design. The only difference between the two is an added glass reinforcement to the wire groove. This is the most beautiful of the Dominion glass insulators. The colours include: clear, light green, light straw, light sage green, dark straw, pink, honey amber, dark red amber, yellow amber, light yellow amber, light yellow, light cornflower blue, cornflower blue and dark cornflower blue. The value of these pieces range from $1 for a clear one to $400 for a dark cornflower blue piece.

CD 164, No. 614 was first produced on April 18, 1927, and production ceased on October 31, 1949 (a short run was produced on March 4, 1954, however). Production of the No. 614 was not great, at least during the later years. Production figures show the following: 1943 - 78,000; 1944 - 77,000; 1949 - 80,000; 1954 - 82,000. CD 164, No. 614 can be found on the sides of houses, used for the power lead-ins. These insulators are found in the following colours: clear, straw, light green, ice green, pink and light sage. The value of CD 164 is only from $1-$4. The major distribution line operating companies of Canada have been the primary users. In the case of No. 614, Ottawa Hydro was a major purchaser.

Drip Points

Drip points were placed on earlier insulators. In the late 1940's, the company learned from major buyers that the drip points were of little importance to them. Therefore, since the cost of molds with drip points was higher than that of those forming a plain skirt, the drip points were eliminated. Drip points were discontinued on CD's 108 and 122 about 1947, and somewhat earlier on CD 154, No. 42. Since a sample of the last 1954 run of CD 164, No. 614, has drip points, it may be assumed that a plain skirt mold was not made for the production of this number.


Production of all insulators was done at the Wallaceburg, Ontario plant except for two short time periods when the insulator press was moved to another plant due to heavy demand in that area. The press was moved to the Company's plant at Redcliff, Alberta on July 21, 1942 and was returned to Wallaceburg on August 31, 1942. During this period, about one month's operation, CD 154, No. 42 insulators were produced. On March 9, 1943, the press was moved to the Company's plant at Point St. Charles, near Montreal, Quebec. The press was in operation there for about six months and was returned to Wallaceburg on September 25, 1943.

Everyone loves insulators in deep colours. Purples, blues and ambers attract our attention, and our dollars! But did you know that coloured glass insulator production was discontinued because insects found them just as attractive as we do?

Early insulators were produced in a variety of colours. However, beginning around 1945, only clear or nearly clear glass was used. This was due partially to buyers' complaints that the coloured insulators offered a more attractive nesting place for insects. It seems they preferred to nest under the partial darkness which the coloured skirts offered, thus decreasing the insulating value of the surface of the insulator's skirt or skirts. By 1959, insulators were made from the same clear glass batch as were tumblers, bottles and other glassware.


Dominion insulators manufactured in the later years of production bear the name DOMINION followed by a dash and the design number on one of the half-molds. On the opposite half-mold is the trademark, which consists of a number representing the last two digits of the year of manufacture, a diamond, and below the diamond another number representing the mold in which the insulator was made. The above arrangement is in accord with Northern Electric specifications furnished to Dominion Glass Co. on October 19, 1953. These specifications stipulated that the lettering molded on the skirt of the insulator should not be over 3/16 of an inch above the surface, and should include the name of the manufacturer and the last two digits of the year of manufacture, plus dots if desired to indicate years in addition to the year number used. This dot system can be found arranged around the diamond trademark usually above the left side of the D within the diamond.

For the earlier years, there is no definite information as to the numbering codes, but it seems that only mold numbers were used at one time, without date numbers. Also, it is possible that only the last digit of the year was used for a time.

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Last updated Tuesday, September 29, 1998