December 4, 2008
Insulators were originally made to keep telegraph and telephone wires electrically insulated from wooden telephone poles (especially important in the rain). With the additional needs of rural electrification, there was a big insulator boom in the early 20th century, peaking from the 1920s through the 1940s, with production in the millions per year.
Made from glass or porcelain, in a dazzling array of shapes and colors (e.g. amber, cobalt blue, green, purple), they’re prized for color, beauty, and rarity. Collectors identify insulators by manufacturer (e.g. Hemingray) and by CD numbers, which are based on shape.
Some insulators were embossed with the manufacturer’s name and style number, and perhaps the year or mold number. The molds were engraved so the letters were dug in. There are a lot of unembossed insulators out there, but at the turn of the century there were a lot of engravers and glass makers and cast iron was very big so people were making a lot of molds, and embossing was very big. As the years went on, there were fewer engravers available and the embossing started getting simpler and simpler.
I got interested in insulators when I lived in El Cajon and my neighbor worked for San Diego Gas and Electric… [more]
For an explosion of color and a quick education on the many beautiful varieties of insulators, blown glass bricks, … [more]
Bill Meier's reference site by and for insulator collectors includes event listings, reference information, photo g… [more]
Christian Willis' well-organized database of Hemingray insulators. Browse over 300 photos by CD number, style, or s… [more]
Shaun Kotlarsky's tribute to the Hemingray Glass Company. While known for its insulators, this site also showcases … [more]
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