Canadian Line Material Ltd. 

Jack Tod's column way back in the November 1980 issue of Crown Jewels carried a question from me about a "what's it" foreign porcelain insulator (or part of one) that turned out to be a primary circuit wireholder. Thanks to its former owner, who did not like metal parts mixed with his insulators, it was missing the lag screw. And who am I to talk! Because that part about the metal sounds familiar, and I have come a long way! 

The green ink marking on the insulator was one I had not seen before. Jack's answer to my question about that was as follows: "I've seen the circle-CLM marking before, but can't attribute it. It's so similar to the Line Material Co. trademark, it could be connected with that, and especially since L-M had dozens of patents on various wireholders. The green underglaze marking is unusual for U.S. pole-line insulators, but not for those made in Canada. If you somehow manage to put all that together and come up with Canadian Line Material Co., that's attributable to your own crystal ball, not mine!" 

The two marking in question are shown below. 

Line Material Co.

Canadian Line Material Co.?

Well, Jack, someone has finally supplied the answer! His name is Mr. Phil McLaughlin from Morton Grove, Illinois. He is not an insulator collector and did not realize I wanted to know, until my friend Lu Farin (Decatur, Texas) tipped him off. He did write me then, and had quite a lot of good information. He was employed by Line Material Co. from 1949-1959, and was able to verify that the circle-CLM trademark did indeed belong to its Canadian subsidiary company, called Canadian Line Material Ltd., organized in the 1930's and known generally as CLM, to differentiate it from LM for the U.S. company.

Each was a corporate entity. CLM was located in Scarborough, Ontario (near Toronto). The U.S. Line Material Co., located in Milwaukee, existed from 1910-1950, when it was bought by and became a subsidiary of McGraw Electric Co. In 1951 McGraw Electric bought the Jeffery-Dewitt Porcelain Co. in Kenova, West Virginia, and arranged for Line Material Co. to take over its management. Unfortunately, a year later, the plant burned to the ground and was never rebuilt.

Subsequently, in 1953, McGraw Electric purchased another plant, that of Illinois Electric Porcelain Co., at McComb, Illinois. Once again, Line Material was chosen to operate the plant. The old Illinois Electric Porcelain Co. was principally in the "specialty" porcelain business, though they did manufacture some insulators for overhead distribution lines. They also made porcelain for the plumbing industry. (It is of interest here to quote from Jack Tod's book Porcelain Insulators, Second Edition: "Illinois once made and catalogued five different foreign type insulators -- white glaze -- for export.") However, when Line Material began to manage the plant, they phased out sanitary porcelain and changed over the facility to the exclusive production of porcelain for utilities and specialty porcelains to be used by manufacturers of electrical equipment.

The Canadian Line Material plant in Ontario concentrated mainly on the production of electrical equipment, and while some manufacturing took place there, much of what was made was merely assembled rather than manufactured, parts coming, I'm sure, from the U.S. Line Material Co.

In 1957 Line Material Co. became a division of McGraw-Edison, a new company, formed by the merger of McGraw Edison Co. and Thomas A. Edison Industries. In 1958 the L-M trademark began to be used on their insulators, and it was probably about this time that electrical equipment supplied by Canadian Line Material Ltd. became identified by their logo, CLM. 

In 1967 Line Material Co. lost its identity with other divisions of McGraw-Edison when the Power Systems Division of the overall conglomerate McGraw-Edison was formed. From that time on the LM trademark was discontinued, and insulators were marked with the letters ME for McGraw-Edison. For more detailed information about these various U.S. companies and their markings, please refer to Jack Tod's Porcelain Insulators, a Guidebook for Collectors, Second Edition. 

Canadian Line Material Ltd. is no longer in business. For reasons unknown, the plant closed down sometime between 1972 and 1975. Many thanks to you, Phil McLaughlin, for solving the mystery of the CLM marking.