Insulators Excite Special Breed of Glass Enthusiasts

Just what is an insulator and why is it collectible?

I asked an avid collector this question and learned a lot. Since I knew what a glass insulator looked like up close, I was puzzled by the fascination that folks find in collecting these utilitarian objects made of heavy glass.

Glass insulators were first produced in the 1850s for use with telegraph lines. (Insulators resist the flow of electricity while supporting wires, so they’re important inventions.) As communications technology continued to develop, insulators were needed more and more, for telephone lines, electric power lines and other applications.

In the mid-1960s, a few people began collecting antique insulators and the craze caught on. The glass objects are commonly around 5 inches tall, weigh over a pound each and can be found in many different colors, except red. Clear, aqua, blues and greens are the most common.

Today there are thousands of collectors, clubs, national shows and reference books available that enthusiasts seek, save and share in their insulator madness.

I spoke with an avid collector, Tim Grantz, from just north of Pittsburgh not long ago. He got in touch with me via this column, in regards to an insulator show held in Natrona Heights, Pa.

“I got interested as a little kid, walking the railroad track,” said Grantz, who has lives about 30 miles north of Pittsburgh in West Leechburg, Pa., his whole life. Glass insulators could often be found around railroad tracks, encased in mud or discarded by workers replacing them. Most of the time, workers didn’t haul the old insulators back because they were quite heavy.

Grantz explained that we have good insulators in the tri-state region because of all the old glass houses. He is a member of an area club and the national club and mentions that both of these groups are great clubs for my readers to explore. Explore the National Insulator Association, found online at

Collectors like Grantz enjoy trading, saving and displaying their treasures. Many enthusiasts got started in the hobby in much the same way, by stumbling across one of these glass novelties while walking.

North American threaded glass pin-type insulators are the most commonly found type of insulator. Collectors use a numbering system for identification that refers to CD 104 or CD 105, meaning Consolidated Design. This handy numbering system was developed by early collector N.R. Woodward. Lots of insulator information can be found on the Internet and in several great reference books.

Collector shows offer a chance to get appraisals, buy, sell and trade items. They are the perfect place to learn about this hobby that gives many people pleasure.

If you are looking to start a collection, the price for nice examples of common insulators range from $5 to $30. The most expensive rare Boston Bottle Work models or Beaver Falls Glass insulators might go as high as $10,000 in certain rare colors! Cobalt is very desirable.

The most common color is aqua and it came about because the glass workers would mix all the glass together at the end of the day and variations of this shade were the result.

The insulator industry went ceramic in recent years because it was cheaper. Ceramic versions are collected now, too. Early porcelain examples exist and are included in the mix, but the glass ones remain the big deal and offer a beautiful display when shown near a window or other light. I use a Hemingray example as a unique paperweight.

For comments or suggestions on local treasures to be featured in Antique of the Week, Maureen Zambito can be reached via email at: or by writing in care of this newspaper.